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extmod/machine_i2c: Use writes not reads in i2c.scan(). 

As per discussion in #2449, using write requests instead of read requests
for I2C.scan() seems to support a larger number of devices, especially
ones that are write-only.  Even a read-only I2C device has to implement
writes in order to be able to receive the address of the register to read.
This commit is contained in:
Radomir Dopieralski 2016-10-08 17:34:46 +02:00 committed by Damien George
parent 9e1dec1818
commit eaef6b5324
1 changed files with 1 additions and 1 deletions
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extmod/machine_i2c.c
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@ -272,7 +272,7 @@ STATIC mp_obj_t machine_i2c_scan(mp_obj_t self_in) {
// 7-bit addresses 0b0000xxx and 0b1111xxx are reserved // 7-bit addresses 0b0000xxx and 0b1111xxx are reserved
for (int addr = 0x08; addr < 0x78; ++addr) { for (int addr = 0x08; addr < 0x78; ++addr) {
mp_hal_i2c_start(self); mp_hal_i2c_start(self);
int ack = mp_hal_i2c_write_byte(self, (addr << 1) | 1); int ack = mp_hal_i2c_write_byte(self, (addr << 1));
if (ack) { if (ack) {
mp_obj_list_append(list, MP_OBJ_NEW_SMALL_INT(addr)); mp_obj_list_append(list, MP_OBJ_NEW_SMALL_INT(addr));
} }