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extmod/machine_i2c: Raise an error when clock stretching times out

pull/2640/head
Radomir Dopieralski 8 years ago
committed by Damien George
parent
702928915c
commit
9a82b67f39
1 changed files with 53 additions and 25 deletions
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  1. 72
      extmod/machine_i2c.c

72
extmod/machine_i2c.c
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@ -52,13 +52,16 @@ STATIC void mp_hal_i2c_scl_low(machine_i2c_obj_t *self) {
mp_hal_pin_od_low(self->scl);
}
STATIC void mp_hal_i2c_scl_release(machine_i2c_obj_t *self) {
STATIC int mp_hal_i2c_scl_release(machine_i2c_obj_t *self) {
uint32_t count = self->us_timeout;
mp_hal_pin_od_high(self->scl);
mp_hal_i2c_delay(self);
// For clock stretching, wait for the SCL pin to be released, with timeout.
for (uint32_t count = self->us_timeout; mp_hal_pin_read(self->scl) == 0 && count; --count) {
for (; mp_hal_pin_read(self->scl) == 0 && count; --count) {
mp_hal_delay_us_fast(1);
}
return count != 0;
}
STATIC void mp_hal_i2c_sda_low(machine_i2c_obj_t *self) {
@ -73,21 +76,23 @@ STATIC int mp_hal_i2c_sda_read(machine_i2c_obj_t *self) {
return mp_hal_pin_read(self->sda);
}
STATIC void mp_hal_i2c_start(machine_i2c_obj_t *self) {
STATIC int mp_hal_i2c_start(machine_i2c_obj_t *self) {
mp_hal_i2c_sda_release(self);
mp_hal_i2c_delay(self);
mp_hal_i2c_scl_release(self);
int ret = mp_hal_i2c_scl_release(self);
mp_hal_i2c_sda_low(self);
mp_hal_i2c_delay(self);
return ret;
}
STATIC void mp_hal_i2c_stop(machine_i2c_obj_t *self) {
STATIC int mp_hal_i2c_stop(machine_i2c_obj_t *self) {
mp_hal_i2c_delay(self);
mp_hal_i2c_sda_low(self);
mp_hal_i2c_delay(self);
mp_hal_i2c_scl_release(self);
int ret = mp_hal_i2c_scl_release(self);
mp_hal_i2c_sda_release(self);
mp_hal_i2c_delay(self);
return ret;
}
STATIC void mp_hal_i2c_init(machine_i2c_obj_t *self, uint32_t freq) {
@ -97,7 +102,7 @@ STATIC void mp_hal_i2c_init(machine_i2c_obj_t *self, uint32_t freq) {
}
mp_hal_pin_open_drain(self->scl);
mp_hal_pin_open_drain(self->sda);
mp_hal_i2c_stop(self);
mp_hal_i2c_stop(self); // ignore error
}
STATIC int mp_hal_i2c_write_byte(machine_i2c_obj_t *self, uint8_t val) {
@ -111,13 +116,17 @@ STATIC int mp_hal_i2c_write_byte(machine_i2c_obj_t *self, uint8_t val) {
mp_hal_i2c_sda_low(self);
}
mp_hal_i2c_delay(self);
mp_hal_i2c_scl_release(self);
if (!mp_hal_i2c_scl_release(self)) {
return 0; // failure
}
mp_hal_i2c_scl_low(self);
}
mp_hal_i2c_sda_release(self);
mp_hal_i2c_delay(self);
mp_hal_i2c_scl_release(self);
if (!mp_hal_i2c_scl_release(self)) {
return 0; // failure
}
int ret = mp_hal_i2c_sda_read(self);
mp_hal_i2c_delay(self);
@ -133,7 +142,9 @@ STATIC int mp_hal_i2c_read_byte(machine_i2c_obj_t *self, uint8_t *val, int nack)
uint8_t data = 0;
for (int i = 7; i >= 0; i--) {
mp_hal_i2c_scl_release(self);
if (!mp_hal_i2c_scl_release(self)) {
return 0;
}
data = (data << 1) | mp_hal_i2c_sda_read(self);
mp_hal_i2c_scl_low(self);
mp_hal_i2c_delay(self);
@ -145,7 +156,9 @@ STATIC int mp_hal_i2c_read_byte(machine_i2c_obj_t *self, uint8_t *val, int nack)
mp_hal_i2c_sda_low(self);
}
mp_hal_i2c_delay(self);
mp_hal_i2c_scl_release(self);
if (!mp_hal_i2c_scl_release(self)) {
return 0; // failure
}
mp_hal_i2c_scl_low(self);
mp_hal_i2c_sda_release(self);
@ -169,7 +182,9 @@ STATIC int mp_hal_i2c_write_addresses(machine_i2c_obj_t *self, uint8_t addr,
STATIC void mp_hal_i2c_write_mem(machine_i2c_obj_t *self, uint8_t addr,
uint32_t memaddr, uint8_t addrsize, const uint8_t *src, size_t len) {
// start the I2C transaction
mp_hal_i2c_start(self);
if (!mp_hal_i2c_start(self)) {
goto er;
}
// write the slave address and the memory address within the slave
if (!mp_hal_i2c_write_addresses(self, addr, memaddr, addrsize)) {
@ -184,18 +199,22 @@ STATIC void mp_hal_i2c_write_mem(machine_i2c_obj_t *self, uint8_t addr,
}
// finish the I2C transaction
mp_hal_i2c_stop(self);
if (!mp_hal_i2c_stop(self)) {
goto er;
}
return;
er:
mp_hal_i2c_stop(self);
mp_hal_i2c_stop(self); // ignore error
nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "I2C bus error"));
}
STATIC void mp_hal_i2c_read_mem(machine_i2c_obj_t *self, uint8_t addr,
uint32_t memaddr, uint8_t addrsize, uint8_t *dest, size_t len) {
// start the I2C transaction
mp_hal_i2c_start(self);
if (!mp_hal_i2c_start(self)) {
goto er;
}
if (addrsize) {
// write the slave address and the memory address within the slave
@ -204,7 +223,9 @@ STATIC void mp_hal_i2c_read_mem(machine_i2c_obj_t *self, uint8_t addr,
}
// i2c_read will do a repeated start, and then read the I2C memory
mp_hal_i2c_start(self);
if (!mp_hal_i2c_start(self)) {
goto er;
}
}
if (!mp_hal_i2c_write_byte(self, (addr << 1) | 1)) {
@ -215,11 +236,13 @@ STATIC void mp_hal_i2c_read_mem(machine_i2c_obj_t *self, uint8_t addr,
goto er;
}
}
mp_hal_i2c_stop(self);
if (!mp_hal_i2c_stop(self)) {
goto er;
}
return;
er:
mp_hal_i2c_stop(self);
mp_hal_i2c_stop(self); // ignore error
nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "I2C bus error"));
}
@ -271,12 +294,13 @@ STATIC mp_obj_t machine_i2c_scan(mp_obj_t self_in) {
mp_obj_t list = mp_obj_new_list(0, NULL);
// 7-bit addresses 0b0000xxx and 0b1111xxx are reserved
for (int addr = 0x08; addr < 0x78; ++addr) {
mp_hal_i2c_start(self);
if (mp_hal_i2c_start(self)) {
int ack = mp_hal_i2c_write_byte(self, (addr << 1));
if (ack) {
mp_obj_list_append(list, MP_OBJ_NEW_SMALL_INT(addr));
}
mp_hal_i2c_stop(self);
mp_hal_i2c_stop(self); // ignore error
}
}
return list;
}
@ -284,14 +308,18 @@ MP_DEFINE_CONST_FUN_OBJ_1(machine_i2c_scan_obj, machine_i2c_scan);
STATIC mp_obj_t machine_i2c_start(mp_obj_t self_in) {
machine_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
mp_hal_i2c_start(self);
if (!mp_hal_i2c_start(self)) {
nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "I2C bus error"));
}
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_1(machine_i2c_start_obj, machine_i2c_start);
STATIC mp_obj_t machine_i2c_stop(mp_obj_t self_in) {
machine_i2c_obj_t *self = MP_OBJ_TO_PTR(self_in);
mp_hal_i2c_stop(self);
if (!mp_hal_i2c_stop(self)) {
nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "I2C bus error"));
}
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_1(machine_i2c_stop_obj, machine_i2c_stop);

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