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Various projects using Raspberry Pi
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raspberrypi/st7565-lcd/ada/bcm2835.c

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// bcm2835.c
// C and C++ support for Broadcom BCM 2835 as used in Raspberry Pi
// http://elinux.org/RPi_Low-level_peripherals
// http://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf
//
// Author: Mike McCauley
// Copyright (C) 2011-2013 Mike McCauley
// $Id: bcm2835.c,v 1.12 2013/09/01 00:56:56 mikem Exp mikem $
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include "bcm2835.h"
// This define enables a little test program (by default a blinking output on pin RPI_GPIO_PIN_11)
// You can do some safe, non-destructive testing on any platform with:
// gcc bcm2835.c -D BCM2835_TEST
// ./a.out
//#define BCM2835_TEST
// Uncommenting this define compiles alternative I2C code for the version 1 RPi
// The P1 header I2C pins are connected to SDA0 and SCL0 on V1.
// By default I2C code is generated for the V2 RPi which has SDA1 and SCL1 connected.
// #define I2C_V1
// Pointers to the hardware register bases
volatile uint32_t *bcm2835_gpio = MAP_FAILED;
volatile uint32_t *bcm2835_pwm = MAP_FAILED;
volatile uint32_t *bcm2835_clk = MAP_FAILED;
volatile uint32_t *bcm2835_pads = MAP_FAILED;
volatile uint32_t *bcm2835_spi0 = MAP_FAILED;
volatile uint32_t *bcm2835_bsc0 = MAP_FAILED;
volatile uint32_t *bcm2835_bsc1 = MAP_FAILED;
volatile uint32_t *bcm2835_st = MAP_FAILED;
// This variable allows us to test on hardware other than RPi.
// It prevents access to the kernel memory, and does not do any peripheral access
// Instead it prints out what it _would_ do if debug were 0
static uint8_t debug = 0;
// I2C The time needed to transmit one byte. In microseconds.
static int i2c_byte_wait_us = 0;
//
// Low level register access functions
//
void bcm2835_set_debug(uint8_t d)
{
debug = d;
}
// safe read from peripheral
uint32_t bcm2835_peri_read(volatile uint32_t* paddr)
{
if (debug)
{
printf("bcm2835_peri_read paddr %08X\n", (unsigned) paddr);
return 0;
}
else
{
// Make sure we dont return the _last_ read which might get lost
// if subsequent code changes to a different peripheral
uint32_t ret = *paddr;
*paddr; // Read without assigneing to an unused variable
return ret;
}
}
// read from peripheral without the read barrier
uint32_t bcm2835_peri_read_nb(volatile uint32_t* paddr)
{
if (debug)
{
printf("bcm2835_peri_read_nb paddr %08X\n", (unsigned) paddr);
return 0;
}
else
{
return *paddr;
}
}
// safe write to peripheral
void bcm2835_peri_write(volatile uint32_t* paddr, uint32_t value)
{
if (debug)
{
printf("bcm2835_peri_write paddr %08X, value %08X\n", (unsigned) paddr, value);
}
else
{
// Make sure we don't rely on the first write, which may get
// lost if the previous access was to a different peripheral.
*paddr = value;
*paddr = value;
}
}
// write to peripheral without the write barrier
void bcm2835_peri_write_nb(volatile uint32_t* paddr, uint32_t value)
{
if (debug)
{
printf("bcm2835_peri_write_nb paddr %08X, value %08X\n",
(unsigned) paddr, value);
}
else
{
*paddr = value;
}
}
// Set/clear only the bits in value covered by the mask
void bcm2835_peri_set_bits(volatile uint32_t* paddr, uint32_t value, uint32_t mask)
{
uint32_t v = bcm2835_peri_read(paddr);
v = (v & ~mask) | (value & mask);
bcm2835_peri_write(paddr, v);
}
//
// Low level convenience functions
//
// Function select
// pin is a BCM2835 GPIO pin number NOT RPi pin number
// There are 6 control registers, each control the functions of a block
// of 10 pins.
// Each control register has 10 sets of 3 bits per GPIO pin:
//
// 000 = GPIO Pin X is an input
// 001 = GPIO Pin X is an output
// 100 = GPIO Pin X takes alternate function 0
// 101 = GPIO Pin X takes alternate function 1
// 110 = GPIO Pin X takes alternate function 2
// 111 = GPIO Pin X takes alternate function 3
// 011 = GPIO Pin X takes alternate function 4
// 010 = GPIO Pin X takes alternate function 5
//
// So the 3 bits for port X are:
// X / 10 + ((X % 10) * 3)
void bcm2835_gpio_fsel(uint8_t pin, uint8_t mode)
{
// Function selects are 10 pins per 32 bit word, 3 bits per pin
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPFSEL0/4 + (pin/10);
uint8_t shift = (pin % 10) * 3;
uint32_t mask = BCM2835_GPIO_FSEL_MASK << shift;
uint32_t value = mode << shift;
bcm2835_peri_set_bits(paddr, value, mask);
}
// Set output pin
void bcm2835_gpio_set(uint8_t pin)
{
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPSET0/4 + pin/32;
uint8_t shift = pin % 32;
bcm2835_peri_write(paddr, 1 << shift);
}
// Clear output pin
void bcm2835_gpio_clr(uint8_t pin)
{
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPCLR0/4 + pin/32;
uint8_t shift = pin % 32;
bcm2835_peri_write(paddr, 1 << shift);
}
// Set all output pins in the mask
void bcm2835_gpio_set_multi(uint32_t mask)
{
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPSET0/4;
bcm2835_peri_write(paddr, mask);
}
// Clear all output pins in the mask
void bcm2835_gpio_clr_multi(uint32_t mask)
{
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPCLR0/4;
bcm2835_peri_write(paddr, mask);
}
// Read input pin
uint8_t bcm2835_gpio_lev(uint8_t pin)
{
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPLEV0/4 + pin/32;
uint8_t shift = pin % 32;
uint32_t value = bcm2835_peri_read(paddr);
return (value & (1 << shift)) ? HIGH : LOW;
}
// See if an event detection bit is set
// Sigh cant support interrupts yet
uint8_t bcm2835_gpio_eds(uint8_t pin)
{
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPEDS0/4 + pin/32;
uint8_t shift = pin % 32;
uint32_t value = bcm2835_peri_read(paddr);
return (value & (1 << shift)) ? HIGH : LOW;
}
// Write a 1 to clear the bit in EDS
void bcm2835_gpio_set_eds(uint8_t pin)
{
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPEDS0/4 + pin/32;
uint8_t shift = pin % 32;
uint32_t value = 1 << shift;
bcm2835_peri_write(paddr, value);
}
// Rising edge detect enable
void bcm2835_gpio_ren(uint8_t pin)
{
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPREN0/4 + pin/32;
uint8_t shift = pin % 32;
uint32_t value = 1 << shift;
bcm2835_peri_set_bits(paddr, value, value);
}
void bcm2835_gpio_clr_ren(uint8_t pin)
{
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPREN0/4 + pin/32;
uint8_t shift = pin % 32;
uint32_t value = 1 << shift;
bcm2835_peri_set_bits(paddr, 0, value);
}
// Falling edge detect enable
void bcm2835_gpio_fen(uint8_t pin)
{
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPFEN0/4 + pin/32;
uint8_t shift = pin % 32;
uint32_t value = 1 << shift;
bcm2835_peri_set_bits(paddr, value, value);
}
void bcm2835_gpio_clr_fen(uint8_t pin)
{
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPFEN0/4 + pin/32;
uint8_t shift = pin % 32;
uint32_t value = 1 << shift;
bcm2835_peri_set_bits(paddr, 0, value);
}
// High detect enable
void bcm2835_gpio_hen(uint8_t pin)
{
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPHEN0/4 + pin/32;
uint8_t shift = pin % 32;
uint32_t value = 1 << shift;
bcm2835_peri_set_bits(paddr, value, value);
}
void bcm2835_gpio_clr_hen(uint8_t pin)
{
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPHEN0/4 + pin/32;
uint8_t shift = pin % 32;
uint32_t value = 1 << shift;
bcm2835_peri_set_bits(paddr, 0, value);
}
// Low detect enable
void bcm2835_gpio_len(uint8_t pin)
{
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPLEN0/4 + pin/32;
uint8_t shift = pin % 32;
uint32_t value = 1 << shift;
bcm2835_peri_set_bits(paddr, value, value);
}
void bcm2835_gpio_clr_len(uint8_t pin)
{
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPLEN0/4 + pin/32;
uint8_t shift = pin % 32;
uint32_t value = 1 << shift;
bcm2835_peri_set_bits(paddr, 0, value);
}
// Async rising edge detect enable
void bcm2835_gpio_aren(uint8_t pin)
{
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPAREN0/4 + pin/32;
uint8_t shift = pin % 32;
uint32_t value = 1 << shift;
bcm2835_peri_set_bits(paddr, value, value);
}
void bcm2835_gpio_clr_aren(uint8_t pin)
{
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPAREN0/4 + pin/32;
uint8_t shift = pin % 32;
uint32_t value = 1 << shift;
bcm2835_peri_set_bits(paddr, 0, value);
}
// Async falling edge detect enable
void bcm2835_gpio_afen(uint8_t pin)
{
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPAFEN0/4 + pin/32;
uint8_t shift = pin % 32;
uint32_t value = 1 << shift;
bcm2835_peri_set_bits(paddr, value, value);
}
void bcm2835_gpio_clr_afen(uint8_t pin)
{
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPAFEN0/4 + pin/32;
uint8_t shift = pin % 32;
uint32_t value = 1 << shift;
bcm2835_peri_set_bits(paddr, 0, value);
}
// Set pullup/down
void bcm2835_gpio_pud(uint8_t pud)
{
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPPUD/4;
bcm2835_peri_write(paddr, pud);
}
// Pullup/down clock
// Clocks the value of pud into the GPIO pin
void bcm2835_gpio_pudclk(uint8_t pin, uint8_t on)
{
volatile uint32_t* paddr = bcm2835_gpio + BCM2835_GPPUDCLK0/4 + pin/32;
uint8_t shift = pin % 32;
bcm2835_peri_write(paddr, (on ? 1 : 0) << shift);
}
// Read GPIO pad behaviour for groups of GPIOs
uint32_t bcm2835_gpio_pad(uint8_t group)
{
volatile uint32_t* paddr = bcm2835_pads + BCM2835_PADS_GPIO_0_27/4 + group*2;
return bcm2835_peri_read(paddr);
}
// Set GPIO pad behaviour for groups of GPIOs
// powerup value for al pads is
// BCM2835_PAD_SLEW_RATE_UNLIMITED | BCM2835_PAD_HYSTERESIS_ENABLED | BCM2835_PAD_DRIVE_8mA
void bcm2835_gpio_set_pad(uint8_t group, uint32_t control)
{
volatile uint32_t* paddr = bcm2835_pads + BCM2835_PADS_GPIO_0_27/4 + group*2;
bcm2835_peri_write(paddr, control | BCM2835_PAD_PASSWRD);
}
// Some convenient arduino-like functions
// milliseconds
void bcm2835_delay(unsigned int millis)
{
struct timespec sleeper;
sleeper.tv_sec = (time_t)(millis / 1000);
sleeper.tv_nsec = (long)(millis % 1000) * 1000000;
nanosleep(&sleeper, NULL);
}
// microseconds
void bcm2835_delayMicroseconds(uint64_t micros)
{
struct timespec t1;
uint64_t start;
// Calling nanosleep() takes at least 100-200 us, so use it for
// long waits and use a busy wait on the System Timer for the rest.
start = bcm2835_st_read();
if (micros > 450)
{
t1.tv_sec = 0;
t1.tv_nsec = 1000 * (long)(micros - 200);
nanosleep(&t1, NULL);
}
bcm2835_st_delay(start, micros);
}
//
// Higher level convenience functions
//
// Set the state of an output
void bcm2835_gpio_write(uint8_t pin, uint8_t on)
{
if (on)
bcm2835_gpio_set(pin);
else
bcm2835_gpio_clr(pin);
}
// Set the state of a all 32 outputs in the mask to on or off
void bcm2835_gpio_write_multi(uint32_t mask, uint8_t on)
{
if (on)
bcm2835_gpio_set_multi(mask);
else
bcm2835_gpio_clr_multi(mask);
}
// Set the state of a all 32 outputs in the mask to the values in value
void bcm2835_gpio_write_mask(uint32_t value, uint32_t mask)
{
bcm2835_gpio_set_multi(value & mask);
bcm2835_gpio_clr_multi((~value) & mask);
}
// Set the pullup/down resistor for a pin
//
// The GPIO Pull-up/down Clock Registers control the actuation of internal pull-downs on
// the respective GPIO pins. These registers must be used in conjunction with the GPPUD
// register to effect GPIO Pull-up/down changes. The following sequence of events is
// required:
// 1. Write to GPPUD to set the required control signal (i.e. Pull-up or Pull-Down or neither
// to remove the current Pull-up/down)
// 2. Wait 150 cycles ? this provides the required set-up time for the control signal
// 3. Write to GPPUDCLK0/1 to clock the control signal into the GPIO pads you wish to
// modify ? NOTE only the pads which receive a clock will be modified, all others will
// retain their previous state.
// 4. Wait 150 cycles ? this provides the required hold time for the control signal
// 5. Write to GPPUD to remove the control signal
// 6. Write to GPPUDCLK0/1 to remove the clock
//
// RPi has P1-03 and P1-05 with 1k8 pullup resistor
void bcm2835_gpio_set_pud(uint8_t pin, uint8_t pud)
{
bcm2835_gpio_pud(pud);
delayMicroseconds(10);
bcm2835_gpio_pudclk(pin, 1);
delayMicroseconds(10);
bcm2835_gpio_pud(BCM2835_GPIO_PUD_OFF);
bcm2835_gpio_pudclk(pin, 0);
}
void bcm2835_spi_begin(void)
{
// Set the SPI0 pins to the Alt 0 function to enable SPI0 access on them
bcm2835_gpio_fsel(RPI_GPIO_P1_26, BCM2835_GPIO_FSEL_ALT0); // CE1
bcm2835_gpio_fsel(RPI_GPIO_P1_24, BCM2835_GPIO_FSEL_ALT0); // CE0
bcm2835_gpio_fsel(RPI_GPIO_P1_21, BCM2835_GPIO_FSEL_ALT0); // MISO
bcm2835_gpio_fsel(RPI_GPIO_P1_19, BCM2835_GPIO_FSEL_ALT0); // MOSI
bcm2835_gpio_fsel(RPI_GPIO_P1_23, BCM2835_GPIO_FSEL_ALT0); // CLK
// Set the SPI CS register to the some sensible defaults
volatile uint32_t* paddr = bcm2835_spi0 + BCM2835_SPI0_CS/4;
bcm2835_peri_write(paddr, 0); // All 0s
// Clear TX and RX fifos
bcm2835_peri_write_nb(paddr, BCM2835_SPI0_CS_CLEAR);
}
void bcm2835_spi_end(void)
{
// Set all the SPI0 pins back to input
bcm2835_gpio_fsel(RPI_GPIO_P1_26, BCM2835_GPIO_FSEL_INPT); // CE1
bcm2835_gpio_fsel(RPI_GPIO_P1_24, BCM2835_GPIO_FSEL_INPT); // CE0
bcm2835_gpio_fsel(RPI_GPIO_P1_21, BCM2835_GPIO_FSEL_INPT); // MISO
bcm2835_gpio_fsel(RPI_GPIO_P1_19, BCM2835_GPIO_FSEL_INPT); // MOSI
bcm2835_gpio_fsel(RPI_GPIO_P1_23, BCM2835_GPIO_FSEL_INPT); // CLK
}
void bcm2835_spi_setBitOrder(uint8_t order)
{
// BCM2835_SPI_BIT_ORDER_MSBFIRST is the only one suported by SPI0
}
// defaults to 0, which means a divider of 65536.
// The divisor must be a power of 2. Odd numbers
// rounded down. The maximum SPI clock rate is
// of the APB clock
void bcm2835_spi_setClockDivider(uint16_t divider)
{
volatile uint32_t* paddr = bcm2835_spi0 + BCM2835_SPI0_CLK/4;
bcm2835_peri_write(paddr, divider);
}
void bcm2835_spi_setDataMode(uint8_t mode)
{
volatile uint32_t* paddr = bcm2835_spi0 + BCM2835_SPI0_CS/4;
// Mask in the CPO and CPHA bits of CS
bcm2835_peri_set_bits(paddr, mode << 2, BCM2835_SPI0_CS_CPOL | BCM2835_SPI0_CS_CPHA);
}
// Writes (and reads) a single byte to SPI
uint8_t bcm2835_spi_transfer(uint8_t value)
{
volatile uint32_t* paddr = bcm2835_spi0 + BCM2835_SPI0_CS/4;
volatile uint32_t* fifo = bcm2835_spi0 + BCM2835_SPI0_FIFO/4;
// This is Polled transfer as per section 10.6.1
// BUG ALERT: what happens if we get interupted in this section, and someone else
// accesses a different peripheral?
// Clear TX and RX fifos
bcm2835_peri_set_bits(paddr, BCM2835_SPI0_CS_CLEAR, BCM2835_SPI0_CS_CLEAR);
// Set TA = 1
bcm2835_peri_set_bits(paddr, BCM2835_SPI0_CS_TA, BCM2835_SPI0_CS_TA);
// Maybe wait for TXD
while (!(bcm2835_peri_read(paddr) & BCM2835_SPI0_CS_TXD))
;
// Write to FIFO, no barrier
bcm2835_peri_write_nb(fifo, value);
// Wait for DONE to be set
while (!(bcm2835_peri_read_nb(paddr) & BCM2835_SPI0_CS_DONE))
;
// Read any byte that was sent back by the slave while we sere sending to it
uint32_t ret = bcm2835_peri_read_nb(fifo);
// Set TA = 0, and also set the barrier
bcm2835_peri_set_bits(paddr, 0, BCM2835_SPI0_CS_TA);
return ret;
}
// Writes (and reads) an number of bytes to SPI
void bcm2835_spi_transfernb(char* tbuf, char* rbuf, uint32_t len)
{
volatile uint32_t* paddr = bcm2835_spi0 + BCM2835_SPI0_CS/4;
volatile uint32_t* fifo = bcm2835_spi0 + BCM2835_SPI0_FIFO/4;
// This is Polled transfer as per section 10.6.1
// BUG ALERT: what happens if we get interupted in this section, and someone else
// accesses a different peripheral?
// Clear TX and RX fifos
bcm2835_peri_set_bits(paddr, BCM2835_SPI0_CS_CLEAR, BCM2835_SPI0_CS_CLEAR);
// Set TA = 1
bcm2835_peri_set_bits(paddr, BCM2835_SPI0_CS_TA, BCM2835_SPI0_CS_TA);
uint32_t i;
for (i = 0; i < len; i++)
{
// Maybe wait for TXD
while (!(bcm2835_peri_read(paddr) & BCM2835_SPI0_CS_TXD))
;
// Write to FIFO, no barrier
bcm2835_peri_write_nb(fifo, tbuf[i]);
// Wait for RXD
while (!(bcm2835_peri_read(paddr) & BCM2835_SPI0_CS_RXD))
;
// then read the data byte
rbuf[i] = bcm2835_peri_read_nb(fifo);
}
// Wait for DONE to be set
while (!(bcm2835_peri_read_nb(paddr) & BCM2835_SPI0_CS_DONE))
;
// Set TA = 0, and also set the barrier
bcm2835_peri_set_bits(paddr, 0, BCM2835_SPI0_CS_TA);
}
// Writes an number of bytes to SPI
void bcm2835_spi_writenb(char* tbuf, uint32_t len)
{
volatile uint32_t* paddr = bcm2835_spi0 + BCM2835_SPI0_CS/4;
volatile uint32_t* fifo = bcm2835_spi0 + BCM2835_SPI0_FIFO/4;
// This is Polled transfer as per section 10.6.1
// BUG ALERT: what happens if we get interupted in this section, and someone else
// accesses a different peripheral?
// Clear TX and RX fifos
bcm2835_peri_set_bits(paddr, BCM2835_SPI0_CS_CLEAR, BCM2835_SPI0_CS_CLEAR);
// Set TA = 1
bcm2835_peri_set_bits(paddr, BCM2835_SPI0_CS_TA, BCM2835_SPI0_CS_TA);
uint32_t i;
for (i = 0; i < len; i++)
{
// Maybe wait for TXD
while (!(bcm2835_peri_read(paddr) & BCM2835_SPI0_CS_TXD))
;
// Write to FIFO, no barrier
bcm2835_peri_write_nb(fifo, tbuf[i]);
// Read from FIFO to prevent stalling
while (bcm2835_peri_read(paddr) & BCM2835_SPI0_CS_RXD)
(void) bcm2835_peri_read_nb(fifo);
}
// Wait for DONE to be set
while (!(bcm2835_peri_read_nb(paddr) & BCM2835_SPI0_CS_DONE)) {
while (bcm2835_peri_read(paddr) & BCM2835_SPI0_CS_RXD)
(void) bcm2835_peri_read_nb(fifo);
};
// Set TA = 0, and also set the barrier
bcm2835_peri_set_bits(paddr, 0, BCM2835_SPI0_CS_TA);
}
// Writes (and reads) an number of bytes to SPI
// Read bytes are copied over onto the transmit buffer
void bcm2835_spi_transfern(char* buf, uint32_t len)
{
bcm2835_spi_transfernb(buf, buf, len);
}
void bcm2835_spi_chipSelect(uint8_t cs)
{
volatile uint32_t* paddr = bcm2835_spi0 + BCM2835_SPI0_CS/4;
// Mask in the CS bits of CS
bcm2835_peri_set_bits(paddr, cs, BCM2835_SPI0_CS_CS);
}
void bcm2835_spi_setChipSelectPolarity(uint8_t cs, uint8_t active)
{
volatile uint32_t* paddr = bcm2835_spi0 + BCM2835_SPI0_CS/4;
uint8_t shift = 21 + cs;
// Mask in the appropriate CSPOLn bit
bcm2835_peri_set_bits(paddr, active << shift, 1 << shift);
}
void bcm2835_i2c_begin(void)
{
#ifdef I2C_V1
volatile uint32_t* paddr = bcm2835_bsc0 + BCM2835_BSC_DIV/4;
// Set the I2C/BSC0 pins to the Alt 0 function to enable I2C access on them
bcm2835_gpio_fsel(RPI_GPIO_P1_03, BCM2835_GPIO_FSEL_ALT0); // SDA
bcm2835_gpio_fsel(RPI_GPIO_P1_05, BCM2835_GPIO_FSEL_ALT0); // SCL
#else
volatile uint32_t* paddr = bcm2835_bsc1 + BCM2835_BSC_DIV/4;
// Set the I2C/BSC1 pins to the Alt 0 function to enable I2C access on them
bcm2835_gpio_fsel(RPI_V2_GPIO_P1_03, BCM2835_GPIO_FSEL_ALT0); // SDA
bcm2835_gpio_fsel(RPI_V2_GPIO_P1_05, BCM2835_GPIO_FSEL_ALT0); // SCL
#endif
// Read the clock divider register
uint16_t cdiv = bcm2835_peri_read(paddr);
// Calculate time for transmitting one byte
// 1000000 = micros seconds in a second
// 9 = Clocks per byte : 8 bits + ACK
i2c_byte_wait_us = ((float)cdiv / BCM2835_CORE_CLK_HZ) * 1000000 * 9;
}
void bcm2835_i2c_end(void)
{
#ifdef I2C_V1
// Set all the I2C/BSC0 pins back to input
bcm2835_gpio_fsel(RPI_GPIO_P1_03, BCM2835_GPIO_FSEL_INPT); // SDA
bcm2835_gpio_fsel(RPI_GPIO_P1_05, BCM2835_GPIO_FSEL_INPT); // SCL
#else
// Set all the I2C/BSC1 pins back to input
bcm2835_gpio_fsel(RPI_V2_GPIO_P1_03, BCM2835_GPIO_FSEL_INPT); // SDA
bcm2835_gpio_fsel(RPI_V2_GPIO_P1_05, BCM2835_GPIO_FSEL_INPT); // SCL
#endif
}
void bcm2835_i2c_setSlaveAddress(uint8_t addr)
{
// Set I2C Device Address
#ifdef I2C_V1
volatile uint32_t* paddr = bcm2835_bsc0 + BCM2835_BSC_A/4;
#else
volatile uint32_t* paddr = bcm2835_bsc1 + BCM2835_BSC_A/4;
#endif
bcm2835_peri_write(paddr, addr);
}
// defaults to 0x5dc, should result in a 166.666 kHz I2C clock frequency.
// The divisor must be a power of 2. Odd numbers
// rounded down.
void bcm2835_i2c_setClockDivider(uint16_t divider)
{
#ifdef I2C_V1
volatile uint32_t* paddr = bcm2835_bsc0 + BCM2835_BSC_DIV/4;
#else
volatile uint32_t* paddr = bcm2835_bsc1 + BCM2835_BSC_DIV/4;
#endif
bcm2835_peri_write(paddr, divider);
// Calculate time for transmitting one byte
// 1000000 = micros seconds in a second
// 9 = Clocks per byte : 8 bits + ACK
i2c_byte_wait_us = ((float)divider / BCM2835_CORE_CLK_HZ) * 1000000 * 9;
}
// set I2C clock divider by means of a baudrate number
void bcm2835_i2c_set_baudrate(uint32_t baudrate)
{
uint32_t divider;
// use 0xFFFE mask to limit a max value and round down any odd number
divider = (BCM2835_CORE_CLK_HZ / baudrate) & 0xFFFE;
bcm2835_i2c_setClockDivider( (uint16_t)divider );
}
// Writes an number of bytes to I2C
uint8_t bcm2835_i2c_write(const char * buf, uint32_t len)
{
#ifdef I2C_V1
volatile uint32_t* dlen = bcm2835_bsc0 + BCM2835_BSC_DLEN/4;
volatile uint32_t* fifo = bcm2835_bsc0 + BCM2835_BSC_FIFO/4;
volatile uint32_t* status = bcm2835_bsc0 + BCM2835_BSC_S/4;
volatile uint32_t* control = bcm2835_bsc0 + BCM2835_BSC_C/4;
#else
volatile uint32_t* dlen = bcm2835_bsc1 + BCM2835_BSC_DLEN/4;
volatile uint32_t* fifo = bcm2835_bsc1 + BCM2835_BSC_FIFO/4;
volatile uint32_t* status = bcm2835_bsc1 + BCM2835_BSC_S/4;
volatile uint32_t* control = bcm2835_bsc1 + BCM2835_BSC_C/4;
#endif
uint32_t remaining = len;
uint32_t i = 0;
uint8_t reason = BCM2835_I2C_REASON_OK;
// Clear FIFO
bcm2835_peri_set_bits(control, BCM2835_BSC_C_CLEAR_1 , BCM2835_BSC_C_CLEAR_1 );
// Clear Status
bcm2835_peri_write_nb(status, BCM2835_BSC_S_CLKT | BCM2835_BSC_S_ERR | BCM2835_BSC_S_DONE);
// Set Data Length
bcm2835_peri_write_nb(dlen, len);
// pre populate FIFO with max buffer
while( remaining && ( i < BCM2835_BSC_FIFO_SIZE ) )
{
bcm2835_peri_write_nb(fifo, buf[i]);
i++;
remaining--;
}
// Enable device and start transfer
bcm2835_peri_write_nb(control, BCM2835_BSC_C_I2CEN | BCM2835_BSC_C_ST);
// Transfer is over when BCM2835_BSC_S_DONE
while(!(bcm2835_peri_read_nb(status) & BCM2835_BSC_S_DONE ))
{
while ( remaining && (bcm2835_peri_read_nb(status) & BCM2835_BSC_S_TXD ))
{
// Write to FIFO, no barrier
bcm2835_peri_write_nb(fifo, buf[i]);
i++;
remaining--;
}
}
// Received a NACK
if (bcm2835_peri_read(status) & BCM2835_BSC_S_ERR)
{
reason = BCM2835_I2C_REASON_ERROR_NACK;
}
// Received Clock Stretch Timeout
else if (bcm2835_peri_read(status) & BCM2835_BSC_S_CLKT)
{
reason = BCM2835_I2C_REASON_ERROR_CLKT;
}
// Not all data is sent
else if (remaining)
{
reason = BCM2835_I2C_REASON_ERROR_DATA;
}
bcm2835_peri_set_bits(control, BCM2835_BSC_S_DONE , BCM2835_BSC_S_DONE);
return reason;
}
// Read an number of bytes from I2C
uint8_t bcm2835_i2c_read(char* buf, uint32_t len)
{
#ifdef I2C_V1
volatile uint32_t* dlen = bcm2835_bsc0 + BCM2835_BSC_DLEN/4;
volatile uint32_t* fifo = bcm2835_bsc0 + BCM2835_BSC_FIFO/4;
volatile uint32_t* status = bcm2835_bsc0 + BCM2835_BSC_S/4;
volatile uint32_t* control = bcm2835_bsc0 + BCM2835_BSC_C/4;
#else
volatile uint32_t* dlen = bcm2835_bsc1 + BCM2835_BSC_DLEN/4;
volatile uint32_t* fifo = bcm2835_bsc1 + BCM2835_BSC_FIFO/4;
volatile uint32_t* status = bcm2835_bsc1 + BCM2835_BSC_S/4;
volatile uint32_t* control = bcm2835_bsc1 + BCM2835_BSC_C/4;
#endif
uint32_t remaining = len;
uint32_t i = 0;
uint8_t reason = BCM2835_I2C_REASON_OK;
// Clear FIFO
bcm2835_peri_set_bits(control, BCM2835_BSC_C_CLEAR_1 , BCM2835_BSC_C_CLEAR_1 );
// Clear Status
bcm2835_peri_write_nb(status, BCM2835_BSC_S_CLKT | BCM2835_BSC_S_ERR | BCM2835_BSC_S_DONE);
// Set Data Length
bcm2835_peri_write_nb(dlen, len);
// Start read
bcm2835_peri_write_nb(control, BCM2835_BSC_C_I2CEN | BCM2835_BSC_C_ST | BCM2835_BSC_C_READ);
// wait for transfer to complete
while (!(bcm2835_peri_read_nb(status) & BCM2835_BSC_S_DONE))
{
// we must empty the FIFO as it is populated and not use any delay
while (bcm2835_peri_read_nb(status) & BCM2835_BSC_S_RXD)
{
// Read from FIFO, no barrier
buf[i] = bcm2835_peri_read_nb(fifo);
i++;
remaining--;
}
}
// transfer has finished - grab any remaining stuff in FIFO
while (remaining && (bcm2835_peri_read_nb(status) & BCM2835_BSC_S_RXD))
{
// Read from FIFO, no barrier
buf[i] = bcm2835_peri_read_nb(fifo);
i++;
remaining--;
}
// Received a NACK
if (bcm2835_peri_read(status) & BCM2835_BSC_S_ERR)
{
reason = BCM2835_I2C_REASON_ERROR_NACK;
}
// Received Clock Stretch Timeout
else if (bcm2835_peri_read(status) & BCM2835_BSC_S_CLKT)
{
reason = BCM2835_I2C_REASON_ERROR_CLKT;
}
// Not all data is received
else if (remaining)
{
reason = BCM2835_I2C_REASON_ERROR_DATA;
}
bcm2835_peri_set_bits(control, BCM2835_BSC_S_DONE , BCM2835_BSC_S_DONE);
return reason;
}
// Read an number of bytes from I2C sending a repeated start after writing
// the required register. Only works if your device supports this mode
uint8_t bcm2835_i2c_read_register_rs(char* regaddr, char* buf, uint32_t len)
{
#ifdef I2C_V1
volatile uint32_t* dlen = bcm2835_bsc0 + BCM2835_BSC_DLEN/4;
volatile uint32_t* fifo = bcm2835_bsc0 + BCM2835_BSC_FIFO/4;
volatile uint32_t* status = bcm2835_bsc0 + BCM2835_BSC_S/4;
volatile uint32_t* control = bcm2835_bsc0 + BCM2835_BSC_C/4;
#else
volatile uint32_t* dlen = bcm2835_bsc1 + BCM2835_BSC_DLEN/4;
volatile uint32_t* fifo = bcm2835_bsc1 + BCM2835_BSC_FIFO/4;
volatile uint32_t* status = bcm2835_bsc1 + BCM2835_BSC_S/4;
volatile uint32_t* control = bcm2835_bsc1 + BCM2835_BSC_C/4;
#endif
uint32_t remaining = len;
uint32_t i = 0;
uint8_t reason = BCM2835_I2C_REASON_OK;
// Clear FIFO
bcm2835_peri_set_bits(control, BCM2835_BSC_C_CLEAR_1 , BCM2835_BSC_C_CLEAR_1 );
// Clear Status
bcm2835_peri_write_nb(status, BCM2835_BSC_S_CLKT | BCM2835_BSC_S_ERR | BCM2835_BSC_S_DONE);
// Set Data Length
bcm2835_peri_write_nb(dlen, 1);
// Enable device and start transfer
bcm2835_peri_write_nb(control, BCM2835_BSC_C_I2CEN);
bcm2835_peri_write_nb(fifo, regaddr[0]);
bcm2835_peri_write_nb(control, BCM2835_BSC_C_I2CEN | BCM2835_BSC_C_ST);
// poll for transfer has started
while ( !( bcm2835_peri_read_nb(status) & BCM2835_BSC_S_TA ) )
{
// Linux may cause us to miss entire transfer stage
if(bcm2835_peri_read(status) & BCM2835_BSC_S_DONE)
break;
}
// Send a repeated start with read bit set in address
bcm2835_peri_write_nb(dlen, len);
bcm2835_peri_write_nb(control, BCM2835_BSC_C_I2CEN | BCM2835_BSC_C_ST | BCM2835_BSC_C_READ );
// Wait for write to complete and first byte back.
bcm2835_delayMicroseconds(i2c_byte_wait_us * 3);
// wait for transfer to complete
while (!(bcm2835_peri_read_nb(status) & BCM2835_BSC_S_DONE))
{
// we must empty the FIFO as it is populated and not use any delay
while (remaining && bcm2835_peri_read_nb(status) & BCM2835_BSC_S_RXD)
{
// Read from FIFO, no barrier
buf[i] = bcm2835_peri_read_nb(fifo);
i++;
remaining--;
}
}
// transfer has finished - grab any remaining stuff in FIFO
while (remaining && (bcm2835_peri_read_nb(status) & BCM2835_BSC_S_RXD))
{
// Read from FIFO, no barrier
buf[i] = bcm2835_peri_read_nb(fifo);
i++;
remaining--;
}
// Received a NACK
if (bcm2835_peri_read(status) & BCM2835_BSC_S_ERR)
{
reason = BCM2835_I2C_REASON_ERROR_NACK;
}
// Received Clock Stretch Timeout
else if (bcm2835_peri_read(status) & BCM2835_BSC_S_CLKT)
{
reason = BCM2835_I2C_REASON_ERROR_CLKT;
}
// Not all data is sent
else if (remaining)
{
reason = BCM2835_I2C_REASON_ERROR_DATA;
}
bcm2835_peri_set_bits(control, BCM2835_BSC_S_DONE , BCM2835_BSC_S_DONE);
return reason;
}
// Read the System Timer Counter (64-bits)
uint64_t bcm2835_st_read(void)
{
volatile uint32_t* paddr;
uint64_t st;
paddr = bcm2835_st + BCM2835_ST_CHI/4;
st = bcm2835_peri_read(paddr);
st <<= 32;
paddr = bcm2835_st + BCM2835_ST_CLO/4;
st += bcm2835_peri_read(paddr);
return st;
}
// Delays for the specified number of microseconds with offset
void bcm2835_st_delay(uint64_t offset_micros, uint64_t micros)
{
uint64_t compare = offset_micros + micros;
while(bcm2835_st_read() < compare)
;
}
// PWM
void bcm2835_pwm_set_clock(uint32_t divisor)
{
// From Gerts code
divisor &= 0xfff;
// Stop PWM clock
bcm2835_peri_write(bcm2835_clk + BCM2835_PWMCLK_CNTL, BCM2835_PWM_PASSWRD | 0x01);
bcm2835_delay(110); // Prevents clock going slow
// Wait for the clock to be not busy
while ((bcm2835_peri_read(bcm2835_clk + BCM2835_PWMCLK_CNTL) & 0x80) != 0)
bcm2835_delay(1);
// set the clock divider and enable PWM clock
bcm2835_peri_write(bcm2835_clk + BCM2835_PWMCLK_DIV, BCM2835_PWM_PASSWRD | (divisor << 12));
bcm2835_peri_write(bcm2835_clk + BCM2835_PWMCLK_CNTL, BCM2835_PWM_PASSWRD | 0x11); // Source=osc and enable
}
void bcm2835_pwm_set_mode(uint8_t channel, uint8_t markspace, uint8_t enabled)
{
uint32_t control = bcm2835_peri_read(bcm2835_pwm + BCM2835_PWM_CONTROL);
if (channel == 0)
{
if (markspace)
control |= BCM2835_PWM0_MS_MODE;
else
control &= ~BCM2835_PWM0_MS_MODE;
if (enabled)
control |= BCM2835_PWM0_ENABLE;
else
control &= ~BCM2835_PWM0_ENABLE;
}
else if (channel == 1)
{
if (markspace)
control |= BCM2835_PWM1_MS_MODE;
else
control &= ~BCM2835_PWM1_MS_MODE;
if (enabled)
control |= BCM2835_PWM1_ENABLE;
else
control &= ~BCM2835_PWM1_ENABLE;
}
// If you use the barrier here, wierd things happen, and the commands dont work
bcm2835_peri_write_nb(bcm2835_pwm + BCM2835_PWM_CONTROL, control);
// bcm2835_peri_write_nb(bcm2835_pwm + BCM2835_PWM_CONTROL, BCM2835_PWM0_ENABLE | BCM2835_PWM1_ENABLE | BCM2835_PWM0_MS_MODE | BCM2835_PWM1_MS_MODE);
}
void bcm2835_pwm_set_range(uint8_t channel, uint32_t range)
{
if (channel == 0)
bcm2835_peri_write_nb(bcm2835_pwm + BCM2835_PWM0_RANGE, range);
else if (channel == 1)
bcm2835_peri_write_nb(bcm2835_pwm + BCM2835_PWM1_RANGE, range);
}
void bcm2835_pwm_set_data(uint8_t channel, uint32_t data)
{
if (channel == 0)
bcm2835_peri_write_nb(bcm2835_pwm + BCM2835_PWM0_DATA, data);
else if (channel == 1)
bcm2835_peri_write_nb(bcm2835_pwm + BCM2835_PWM1_DATA, data);
}
// Allocate page-aligned memory.
void *malloc_aligned(size_t size)
{
void *mem;
errno = posix_memalign(&mem, BCM2835_PAGE_SIZE, size);
return (errno ? NULL : mem);
}
// Map 'size' bytes starting at 'off' in file 'fd' to memory.
// Return mapped address on success, MAP_FAILED otherwise.
// On error print message.
static void *mapmem(const char *msg, size_t size, int fd, off_t off)
{
void *map = mmap(NULL, size, (PROT_READ | PROT_WRITE), MAP_SHARED, fd, off);
if (MAP_FAILED == map)
fprintf(stderr, "bcm2835_init: %s mmap failed: %s\n", msg, strerror(errno));
return map;
}
static void unmapmem(void **pmem, size_t size)
{
if (*pmem == MAP_FAILED) return;
munmap(*pmem, size);
*pmem = MAP_FAILED;
}
// Initialise this library.
int bcm2835_init(void)
{
if (debug)
{
bcm2835_pads = (uint32_t*)BCM2835_GPIO_PADS;
bcm2835_clk = (uint32_t*)BCM2835_CLOCK_BASE;
bcm2835_gpio = (uint32_t*)BCM2835_GPIO_BASE;
bcm2835_pwm = (uint32_t*)BCM2835_GPIO_PWM;
bcm2835_spi0 = (uint32_t*)BCM2835_SPI0_BASE;
bcm2835_bsc0 = (uint32_t*)BCM2835_BSC0_BASE;
bcm2835_bsc1 = (uint32_t*)BCM2835_BSC1_BASE;
bcm2835_st = (uint32_t*)BCM2835_ST_BASE;
return 1; // Success
}
int memfd = -1;
int ok = 0;
// Open the master /dev/memory device
if ((memfd = open("/dev/mem", O_RDWR | O_SYNC) ) < 0)
{
fprintf(stderr, "bcm2835_init: Unable to open /dev/mem: %s\n",
strerror(errno)) ;
goto exit;
}
// GPIO:
bcm2835_gpio = mapmem("gpio", BCM2835_BLOCK_SIZE, memfd, BCM2835_GPIO_BASE);
if (bcm2835_gpio == MAP_FAILED) goto exit;
// PWM
bcm2835_pwm = mapmem("pwm", BCM2835_BLOCK_SIZE, memfd, BCM2835_GPIO_PWM);
if (bcm2835_pwm == MAP_FAILED) goto exit;
// Clock control (needed for PWM)
bcm2835_clk = mapmem("clk", BCM2835_BLOCK_SIZE, memfd, BCM2835_CLOCK_BASE);
if (bcm2835_clk == MAP_FAILED) goto exit;
bcm2835_pads = mapmem("pads", BCM2835_BLOCK_SIZE, memfd, BCM2835_GPIO_PADS);
if (bcm2835_pads == MAP_FAILED) goto exit;
bcm2835_spi0 = mapmem("spi0", BCM2835_BLOCK_SIZE, memfd, BCM2835_SPI0_BASE);
if (bcm2835_spi0 == MAP_FAILED) goto exit;
// I2C
bcm2835_bsc0 = mapmem("bsc0", BCM2835_BLOCK_SIZE, memfd, BCM2835_BSC0_BASE);
if (bcm2835_bsc0 == MAP_FAILED) goto exit;
bcm2835_bsc1 = mapmem("bsc1", BCM2835_BLOCK_SIZE, memfd, BCM2835_BSC1_BASE);
if (bcm2835_bsc1 == MAP_FAILED) goto exit;
// ST
bcm2835_st = mapmem("st", BCM2835_BLOCK_SIZE, memfd, BCM2835_ST_BASE);
if (bcm2835_st == MAP_FAILED) goto exit;
ok = 1;
exit:
if (memfd >= 0)
close(memfd);
if (!ok)
bcm2835_close();
return ok;
}
// Close this library and deallocate everything
int bcm2835_close(void)
{
if (debug) return 1; // Success
unmapmem((void**) &bcm2835_gpio, BCM2835_BLOCK_SIZE);
unmapmem((void**) &bcm2835_pwm, BCM2835_BLOCK_SIZE);
unmapmem((void**) &bcm2835_clk, BCM2835_BLOCK_SIZE);
unmapmem((void**) &bcm2835_spi0, BCM2835_BLOCK_SIZE);
unmapmem((void**) &bcm2835_bsc0, BCM2835_BLOCK_SIZE);
unmapmem((void**) &bcm2835_bsc1, BCM2835_BLOCK_SIZE);
unmapmem((void**) &bcm2835_st, BCM2835_BLOCK_SIZE);
unmapmem((void**) &bcm2835_pads, BCM2835_BLOCK_SIZE);
return 1; // Success
}
#ifdef BCM2835_TEST
// this is a simple test program that prints out what it will do rather than
// actually doing it
int main(int argc, char **argv)
{
// Be non-destructive
bcm2835_set_debug(1);
if (!bcm2835_init())
return 1;
// Configure some GPIO pins fo some testing
// Set RPI pin P1-11 to be an output
bcm2835_gpio_fsel(RPI_GPIO_P1_11, BCM2835_GPIO_FSEL_OUTP);
// Set RPI pin P1-15 to be an input
bcm2835_gpio_fsel(RPI_GPIO_P1_15, BCM2835_GPIO_FSEL_INPT);
// with a pullup
bcm2835_gpio_set_pud(RPI_GPIO_P1_15, BCM2835_GPIO_PUD_UP);
// And a low detect enable
bcm2835_gpio_len(RPI_GPIO_P1_15);
// and input hysteresis disabled on GPIOs 0 to 27
bcm2835_gpio_set_pad(BCM2835_PAD_GROUP_GPIO_0_27, BCM2835_PAD_SLEW_RATE_UNLIMITED|BCM2835_PAD_DRIVE_8mA);
#if 1
// Blink
while (1)
{
// Turn it on
bcm2835_gpio_write(RPI_GPIO_P1_11, HIGH);
// wait a bit
bcm2835_delay(500);
// turn it off
bcm2835_gpio_write(RPI_GPIO_P1_11, LOW);
// wait a bit
bcm2835_delay(500);
}
#endif
#if 0
// Read input
while (1)
{
// Read some data
uint8_t value = bcm2835_gpio_lev(RPI_GPIO_P1_15);
printf("read from pin 15: %d\n", value);
// wait a bit
bcm2835_delay(500);
}
#endif
#if 0
// Look for a low event detection
// eds will be set whenever pin 15 goes low
while (1)
{
if (bcm2835_gpio_eds(RPI_GPIO_P1_15))
{
// Now clear the eds flag by setting it to 1
bcm2835_gpio_set_eds(RPI_GPIO_P1_15);
printf("low event detect for pin 15\n");
}
// wait a bit
bcm2835_delay(500);
}
#endif
if (!bcm2835_close())
return 1;
return 0;
}
#endif