Commit 6474598c authored by Hagen Kaye's avatar Hagen Kaye
Browse files

Added i2c python interface object

parent b8ecc29f
#include <stdio.h>
#include <stm32f4xx.h>
#include <stm32f4xx_rcc.h>
#include <stm32f4xx_gpio.h>
#include "misc.h"
#include "systick.h"
#include "mpconfig.h"
#include "obj.h"
typedef enum {
PYB_I2C_1 = 0,
PYB_I2C_2 = 1,
} pyb_i2c_t;
typedef enum {
I2C_STATE_IDLE = 0,
I2C_STATE_WRITE = 1,
I2C_STATE_READ = 2,
} i2c_state_t;
// set to true if the port has already been initialized
bool i2c1_port_initialized = false;
bool i2c2_port_initialized = false;
static I2C_TypeDef * _i2c_port_addr(pyb_i2c_t i2c_port)
{
if (i2c_port == PYB_I2C_1)
return I2C1;
if (i2c_port == PYB_I2C_2)
return I2C2;
return NULL;
}
// todo - perhaps there should be some global resource management for gpio
// this function would fail if the i2c pins have already been defined for
// use by another python object
// as it is, this always returns true (unless i2c_port is invalid)
static bool _i2c_init (pyb_i2c_t i2c_port)
{
GPIO_InitTypeDef GPIO_InitStructure;
I2C_TypeDef *i2c = _i2c_port_addr(i2c_port);
if (i2c == NULL)
return false;
if (i2c_port == PYB_I2C_1) {
if (i2c1_port_initialized == true) return true;
RCC->APB1ENR |= RCC_APB1ENR_I2C1EN; // enable I2C1
// PB6=SCL, PB7=SDA
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_OType = GPIO_OType_OD;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_25MHz;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_Init(GPIOB, &GPIO_InitStructure);
// alternate functions for SCL and SDA
GPIO_PinAFConfig(GPIOB, GPIO_PinSource6, GPIO_AF_I2C1);
GPIO_PinAFConfig(GPIOB, GPIO_PinSource7, GPIO_AF_I2C1);
i2c1_port_initialized = true;
}
if (i2c_port == PYB_I2C_2) {
if (i2c2_port_initialized == true) return true;
RCC->APB1ENR |= RCC_APB1ENR_I2C2EN; // enable I2C2
// PB10=SCL, PB11=SDA
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10 | GPIO_Pin_11;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_OType = GPIO_OType_OD;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_25MHz;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_Init(GPIOB, &GPIO_InitStructure);
// alternate functions for SCL and SDA
GPIO_PinAFConfig(GPIOB, GPIO_PinSource10, GPIO_AF_I2C2);
GPIO_PinAFConfig(GPIOB, GPIO_PinSource11, GPIO_AF_I2C2);
i2c2_port_initialized = true;
}
// get clock speeds
RCC_ClocksTypeDef rcc_clocks;
RCC_GetClocksFreq(&rcc_clocks);
// disable the I2C peripheral before we configure it
i2c->CR1 &= ~I2C_CR1_PE;
// program peripheral input clock
i2c->CR2 = 4; // no interrupts; 4 MHz (hopefully!) (could go up to 42MHz)
// configure clock control reg
uint32_t freq = rcc_clocks.PCLK1_Frequency / (100000 << 1); // want 100kHz, this is the formula for freq
i2c->CCR = freq; // standard mode (speed), freq calculated as above
// configure rise time reg
i2c->TRISE = (rcc_clocks.PCLK1_Frequency / 1000000) + 1; // formula for trise, gives maximum rise time
// enable the I2C peripheral
i2c->CR1 |= I2C_CR1_PE;
return true;
}
static uint32_t _i2c_get_sr(pyb_i2c_t i2c_port) {
// must read SR1 first, then SR2, as the read can clear some flags
I2C_TypeDef *i2c = _i2c_port_addr(i2c_port);
if (i2c == NULL) return 0;
uint32_t sr1 = i2c->SR1;
uint32_t sr2 = i2c->SR2;
return (sr2 << 16) | sr1;
}
static bool _i2c_restart(pyb_i2c_t i2c_port, uint8_t addr, int write) {
I2C_TypeDef *i2c = _i2c_port_addr(i2c_port);
if (i2c == NULL) return false;
// send start condition
i2c->CR1 |= I2C_CR1_START;
// wait for BUSY, MSL and SB --> Slave has acknowledged start condition
uint32_t timeout = 1000000;
while ((_i2c_get_sr(i2c_port) & 0x00030001) != 0x00030001) {
if (--timeout == 0) {
//printf("timeout in _i2c_restart\n");
return false;
}
}
if (write) {
// send address and write bit
i2c->DR = (addr << 1) | 0;
// wait for BUSY, MSL, ADDR, TXE and TRA
timeout = 1000000;
while ((_i2c_get_sr(i2c_port) & 0x00070082) != 0x00070082) {
if (--timeout == 0) {
//printf("timeout in _i2c_restart write\n");
return false;
}
}
} else {
// send address and read bit
i2c->DR = (addr << 1) | 1;
// wait for BUSY, MSL and ADDR flags
timeout = 1000000;
while ((_i2c_get_sr(i2c_port) & 0x00030002) != 0x00030002) {
if (--timeout == 0) {
//printf("timeout in _i2c_restart read\n");
return false;
}
}
}
return true;
}
static bool _i2c_send_byte(pyb_i2c_t i2c_port, uint8_t data) {
I2C_TypeDef *i2c = _i2c_port_addr(i2c_port);
if (i2c == NULL) return false;
// send byte
i2c->DR = data;
// wait for TRA, BUSY, MSL, TXE and BTF (byte transmitted)
uint32_t timeout = 1000000;
while ((_i2c_get_sr(i2c_port) & 0x00070084) != 0x00070084) {
if (--timeout == 0) {
//printf("timeout in _i2c_send_byte\n");
return false;
}
}
return true;
}
static uint8_t _i2c_read_ack(pyb_i2c_t i2c_port) {
I2C_TypeDef *i2c = _i2c_port_addr(i2c_port);
if (i2c == NULL) return 0;
// enable ACK of received byte
i2c->CR1 |= I2C_CR1_ACK;
// wait for BUSY, MSL and RXNE (byte received)
uint32_t timeout = 1000000;
while ((_i2c_get_sr(i2c_port) & 0x00030040) != 0x00030040) {
if (--timeout == 0) {
//printf("timeout in _i2c_read_ack\n");
break;
}
}
// read and return data
uint8_t data = i2c->DR;
return data;
}
static uint8_t _i2c_read_nack(pyb_i2c_t i2c_port) {
I2C_TypeDef *i2c = _i2c_port_addr(i2c_port);
if (i2c == NULL) return 0;
// disable ACK of received byte (to indicate end of receiving)
i2c->CR1 &= (uint16_t)~((uint16_t)I2C_CR1_ACK);
// last byte should apparently also generate a stop condition
i2c->CR1 |= I2C_CR1_STOP;
// wait for BUSY, MSL and RXNE (byte received)
uint32_t timeout = 1000000;
while ((_i2c_get_sr(i2c_port) & 0x00030040) != 0x00030040) {
if (--timeout == 0) {
//printf("timeout in _i2c_read_nack\n");
break;
}
}
// read and return data
uint8_t data = i2c->DR;
return data;
}
static bool _i2c_start(pyb_i2c_t i2c_port) {
I2C_TypeDef *i2c = _i2c_port_addr(i2c_port);
if (i2c == NULL) return false;
// wait until I2C is not busy
uint32_t timeout = 1000000;
while (i2c->SR2 & I2C_SR2_BUSY) {
if (--timeout == 0) {
return false;
}
}
return true;
}
static void _i2c_stop(pyb_i2c_t i2c_port) {
I2C_TypeDef *i2c = _i2c_port_addr(i2c_port);
if (i2c == NULL) return;
// send stop condition
i2c->CR1 |= I2C_CR1_STOP;
}
/******************************************************************************/
/* Micro Python bindings */
typedef struct _pyb_i2c_obj_t {
mp_obj_base_t base;
pyb_i2c_t i2c_port;
int i2c_addr;
i2c_state_t i2c_state;
} pyb_i2c_obj_t;
void i2c_obj_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t self_in) {
pyb_i2c_obj_t *self = self_in;
print(env, "<I2C%lu addr:%lu>", (unsigned int)self->i2c_port, (unsigned int)self->i2c_addr);
}
// calls _i2c_start with write=0,1 depending on LSB of i2c_addr
mp_obj_t i2c_obj_start(mp_obj_t self_in) {
pyb_i2c_obj_t *self = self_in;
if (self->i2c_state != I2C_STATE_IDLE) {
_i2c_stop(self->i2c_port);
self->i2c_state = I2C_STATE_IDLE;
}
if (_i2c_start(self->i2c_port) == true)
return mp_const_true;
return mp_const_false;
}
mp_obj_t i2c_obj_write(mp_obj_t self_in, mp_obj_t data_in) {
pyb_i2c_obj_t *self = self_in;
if (self->i2c_state != I2C_STATE_WRITE) {
if (_i2c_restart(self->i2c_port, self->i2c_addr, 1) == false) {
_i2c_stop(self->i2c_port);
self->i2c_state = I2C_STATE_IDLE;
return mp_const_false;
}
self->i2c_state = I2C_STATE_WRITE;
}
uint8_t data = mp_obj_get_int(data_in);
if (_i2c_send_byte(self->i2c_port, data) == false)
return mp_const_false;
return mp_const_true;
}
mp_obj_t i2c_obj_read(mp_obj_t self_in) {
pyb_i2c_obj_t *self = self_in;
if (self->i2c_state != I2C_STATE_READ) {
if (_i2c_restart(self->i2c_port, self->i2c_addr, 0) == false) {
_i2c_stop(self->i2c_port);
self->i2c_state = I2C_STATE_IDLE;
return mp_const_false;
}
self->i2c_state = I2C_STATE_READ;
}
uint8_t data = _i2c_read_ack(self->i2c_port);
return mp_obj_new_int(data);
}
mp_obj_t i2c_obj_readAndStop(mp_obj_t self_in) {
pyb_i2c_obj_t *self = self_in;
if (self->i2c_state != I2C_STATE_READ) {
if (_i2c_restart(self->i2c_port, self->i2c_addr, 0) == false) {
_i2c_stop(self->i2c_port);
self->i2c_state = I2C_STATE_IDLE;
return mp_const_false;
}
}
uint8_t data = _i2c_read_nack(self->i2c_port);
self->i2c_state = I2C_STATE_IDLE;
return mp_obj_new_int(data);
}
mp_obj_t i2c_obj_stop(mp_obj_t self_in) {
pyb_i2c_obj_t *self = self_in;
_i2c_stop(self->i2c_port);
self->i2c_state = I2C_STATE_IDLE;
return mp_const_none;
}
static MP_DEFINE_CONST_FUN_OBJ_1(i2c_obj_start_obj, i2c_obj_start);
static MP_DEFINE_CONST_FUN_OBJ_2(i2c_obj_write_obj, i2c_obj_write);
static MP_DEFINE_CONST_FUN_OBJ_1(i2c_obj_read_obj, i2c_obj_read);
static MP_DEFINE_CONST_FUN_OBJ_1(i2c_obj_readAndStop_obj, i2c_obj_readAndStop);
static MP_DEFINE_CONST_FUN_OBJ_1(i2c_obj_stop_obj, i2c_obj_stop);
static const mp_obj_type_t i2c_obj_type = {
{ &mp_const_type },
"I2C",
i2c_obj_print, // print
NULL, // call_n
NULL, // unary_op
NULL, // binary_op
NULL, // getiter
NULL, // iternext
{ // method list
{ "start", &i2c_obj_start_obj },
{ "write", &i2c_obj_write_obj },
{ "read", &i2c_obj_read_obj },
{ "readAndStop", &i2c_obj_readAndStop_obj },
{ "stop", &i2c_obj_stop_obj },
{ NULL, NULL },
}
};
// create the I2C object
// currently support either I2C1 (i2c_id = 0) or I2C2 (i2c_id = 1)
mp_obj_t pyb_I2C(mp_obj_t i2c_id, mp_obj_t i2c_addr) {
pyb_i2c_t i2c_port;
switch(mp_obj_get_int(i2c_id)) {
case 0: i2c_port = PYB_I2C_1; break;
case 1: i2c_port = PYB_I2C_2; break;
default: return mp_const_none;
}
if (_i2c_init(i2c_port) == false)
return mp_const_none;
pyb_i2c_obj_t *o = m_new_obj(pyb_i2c_obj_t);
o->base.type = &i2c_obj_type;
o->i2c_port = i2c_port;
o->i2c_addr = mp_obj_get_int(i2c_addr);
o->i2c_state = I2C_STATE_IDLE;
return o;
}
mp_obj_t pyb_I2C(mp_obj_t i2c_id, mp_obj_t i2c_addr);
Supports Markdown
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment