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// bcm2835.c
// 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 1.10 2013/03/18 05:57:36 mikem Exp mikem $
//
// 03/17/2013 : Charles-Henri Hallard (http://hallard.me)
// Modified Adding some fonctionnalities
// Added millis() function
// Added option to use custom Chip Select Pin PI GPIO instead of only CE0 CE1
// Done a hack to use CE1 by software as custom CS pin because HW does not work
// Added function to determine PI revision board
// Added function to set SPI speed (instead of divider for easier look in code)
// 06/29/2013 Incorporated latest version of bcm2825.h done by Mike McCauley
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/i2c-dev.h>
#include <errno.h>
#include <sys/mman.h>
#include <string.h>
#include <sys/time.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
// 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;
// i2c file descriptor for opeping i2c device
static int i2c_fd = 0;
// SPI Custom Chip Select Pin
static int spi_custom_cs = 0;
// Time for millis function
static unsigned long long epoch ;
//
// Low level register access functions
//
void bcm2835_set_debug(uint8_t d)
{
debug = d;
}
// Get raspberry PI model version
int bcm2835_get_pi_version( void )
{
int rev = 0;
char buff[512];
char * p;
char * pend;
FILE * fd ;
// do some clean up
memset(buff,0,sizeof(buff));
fd = fopen("/proc/cpuinfo","r");
// Opened successfully
if( fd )
{
//printf("File opened successfully through fopen()\n");
// parse each line until we the end or we find the good one
while( fgets(buff, sizeof(buff), fd) != NULL && rev ==0 )
{
// search
if( (strstr(buff, "Revision" )) != NULL )
{
// point to the separator ":" format is has follow
// Revision : 000f
if ( (p = strtok( buff, ":")) != NULL )
{
// Ok get value
if ( (p = strtok( NULL, ":")) != NULL )
{
// Revision Version is in hex format so put 0x before the number
*p = 'x';
*--p = '0';
// convert to number
rev = strtol(p, &pend, 16);
//printf("rev=%d 0x%04x\n", rev, rev);
// not Okay ?
if ( !*pend )
{
rev= 0;
}
else
{
// Revision 1 or 2 ?
rev = (rev < 4 ) ? 1 : 2 ;
}
}
}
}
}
// Close the file.
if(fd)
{
fclose(fd);
}
}
return rev;
}
// 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;
uint32_t dummy = *paddr;
dummy=dummy; // avoid compiler warning
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);
}
// 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);
}
// This function is added in order to simulate arduino millis() function
unsigned int bcm2835_millis(void)
{
struct timeval now;
unsigned long long ms;
gettimeofday(&now, NULL);
ms = (now.tv_sec * 1000000 + now.tv_usec) / 1000 ;
return ((uint32_t) (ms - epoch ));
}
//
// 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(uint8_t cs)
{
volatile uint32_t* paddr = bcm2835_spi0 + BCM2835_SPI0_CS/4;
// Set the SPI0 pins to the Alt 0 function to enable SPI0 access on them
// except if we need custom Chip Select Pin
// printf("bcm2835_spi_begin -> spi_custom_cs = %d \n",cs );
// Do we need custom chip select control or
// drive CE1 manually (because CE1 does not work with hardware)
if ( cs > BCM2835_SPI_CS_NONE || cs == BCM2835_SPI_CS1 )
{
// indicate we will use a custom GPIO port
spi_custom_cs = cs ;
// ok hard CE1 not working, drive it manually
if (cs == BCM2835_SPI_CS1 )
{
// Dirty Hack CE1 in now custom Chip Select GPIO 26
// the real CE1 pin
spi_custom_cs = RPI_GPIO_P1_26 ;
bcm2835_gpio_fsel(spi_custom_cs, BCM2835_GPIO_FSEL_OUTP);
bcm2835_gpio_write(spi_custom_cs, HIGH);
}
// Mask in we use custom CS (not sure it has a real effect)
bcm2835_peri_set_bits(paddr, BCM2835_SPI_CS_NONE, BCM2835_SPI0_CS_CS);
}
// Ok hardware driving of chip select
else
{
// Just in case
spi_custom_cs = 0 ;
// Mask in the CS bits of CS
bcm2835_peri_set_bits(paddr, cs, BCM2835_SPI0_CS_CS);
}
// Now we can drive the I/O as asked
if (spi_custom_cs == 0)
{
// Not custom CS, so hardware driven
bcm2835_gpio_fsel(RPI_GPIO_P1_24, BCM2835_GPIO_FSEL_ALT0); // CE0
bcm2835_gpio_fsel(RPI_GPIO_P1_26, BCM2835_GPIO_FSEL_ALT0); // CE1
}
else
{
// so set custom CS as output, High level by default
bcm2835_gpio_fsel(spi_custom_cs, BCM2835_GPIO_FSEL_OUTP); // Custom GPIO
bcm2835_gpio_write(spi_custom_cs, HIGH);
}
// Classic pin, hardware driven
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
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
if (spi_custom_cs == 0)
{
bcm2835_gpio_fsel(RPI_GPIO_P1_26, BCM2835_GPIO_FSEL_INPT); // CE1
bcm2835_gpio_fsel(RPI_GPIO_P1_24, BCM2835_GPIO_FSEL_INPT); // CE0
}
else
{
bcm2835_gpio_fsel(spi_custom_cs, BCM2835_GPIO_FSEL_INPT); // Custom GPIO
}
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
}
// Drive Custom chip select pin
void bcm2835_spi_setChipSelect(uint8_t level)
{
// Do this only if we are using custom ChipSelect I/O
if ( spi_custom_cs > BCM2835_SPI_CS_NONE )
bcm2835_gpio_write(spi_custom_cs, level);
}
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_setClockSpeed(uint16_t speed)
{
bcm2835_spi_setClockDivider( speed);
}
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;
// Custom chip select LOW
bcm2835_spi_setChipSelect(LOW);
// 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))
delayMicroseconds(10);
// 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))
delayMicroseconds(10);
// 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);
// Custom chip select HIGH
bcm2835_spi_setChipSelect(HIGH);
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;
// Custom chip select LOW
bcm2835_spi_setChipSelect(LOW);
// 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))
delayMicroseconds(10);
// Write to FIFO, no barrier
bcm2835_peri_write_nb(fifo, tbuf[i]);
// Wait for RXD
while (!(bcm2835_peri_read(paddr) & BCM2835_SPI0_CS_RXD))
delayMicroseconds(10);
// 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))
delayMicroseconds(10);
// Set TA = 0, and also set the barrier
bcm2835_peri_set_bits(paddr, 0, BCM2835_SPI0_CS_TA);
// Custom chip select HIGH
bcm2835_spi_setChipSelect(HIGH);
}
// 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;
// Custom chip select LOW
bcm2835_spi_setChipSelect(LOW);
// This is Polled transfer as per section 10.6.1
// BUG ALERT: what happens if we get interrupted 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 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);
// Custom chip select HIGH
bcm2835_spi_setChipSelect(HIGH);
}
// 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)
{
// All is done now in bcm2835_spi_begin()
}
void bcm2835_spi_setChipSelectPolarity(uint8_t cs, uint8_t active)
{
volatile uint32_t* paddr = bcm2835_spi0 + BCM2835_SPI0_CS/4;
// only valid for no custom CS
if (cs <= BCM2835_SPI_CS_NONE)
{
uint8_t shift = 21 + cs;
// Mask in the appropriate CSPOLn bit
bcm2835_peri_set_bits(paddr, active << shift, 1 << shift);
}
}
int bcm2835_i2c_begin(void)
{
int fd ;
if ((fd = open (bcm2835_get_pi_version() == 1 ? "/dev/i2c-0":"/dev/i2c-1" , O_RDWR)) < 0)
return fd;
// Set i2c descriptor
i2c_fd = fd;
return i2c_fd ;
}
void bcm2835_i2c_end(void)
{
// close i2c bus
if ( i2c_fd )
{
close(i2c_fd);
i2c_fd = 0;
}
}
int bcm2835_i2c_setSlaveAddress(uint8_t addr)
{
if (!i2c_fd)
return (-1);
// Set I2C Device Address
return (ioctl (i2c_fd, I2C_SLAVE, addr) );
}
// set I2C clock divider by means of a baudrate number
void bcm2835_i2c_set_baudrate(uint32_t baudrate)
{
volatile uint32_t* paddr = bcm2835_bsc1 + BCM2835_BSC_DIV/4;
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_peri_write(paddr, divider);
}
// Writes an number of bytes to I2C
int bcm2835_i2c_write(const char * buf, uint32_t len)
{
int reason = -1 ;
if (!i2c_fd)
return (-1);
// Do simple use of I2C smbus command regarding number of bytes to transfer
// Write 1 byte
if (len == 2)
reason = i2c_smbus_write_byte_data(i2c_fd, buf[0], buf[1]);
// Write 1 word
else if (len == 3)
reason = i2c_smbus_write_word_data(i2c_fd, buf[0], (buf[2]<<8) | buf[1] );
// Write bulk data
else
reason = i2c_smbus_write_i2c_block_data(i2c_fd, buf[0], len-1, (const __u8 *) &buf[1]);
usleep(1);
return ( reason );
}
// Read an number of bytes from I2C
// to do
uint8_t bcm2835_i2c_read(char* buf, uint32_t len)
{
uint8_t reason = 0;
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)
;
}
// 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)
{
struct timeval tv ;
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();
gettimeofday (&tv, NULL) ;
epoch = (tv.tv_sec * 1000000 + tv.tv_usec) / 1000 ;
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);
return 1; // Success
}
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