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Allow writing buffer of length zero to I2C device; it can be used to poll for existence.

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This commit is contained in:
Dan Halbert 2017-10-30 19:32:03 -04:00 committed by Scott Shawcroft
parent bd7abcda97
commit f738996164
2 changed files with 6 additions and 4 deletions
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8
shared-bindings/busio/I2C.c
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@ -171,6 +171,7 @@ MP_DEFINE_CONST_FUN_OBJ_1(busio_i2c_unlock_obj, busio_i2c_obj_unlock);
//|
//| Read into ``buffer`` from the slave specified by ``address``.
//| The number of bytes read will be the length of ``buffer``.
//| At least one byte must be read.
//|
//| If ``start`` or ``end`` is provided, then the buffer will be sliced
//| as if ``buffer[start:end]``. This will not cause an allocation like
@ -223,6 +224,9 @@ MP_DEFINE_CONST_FUN_OBJ_KW(busio_i2c_readfrom_into_obj, 3, busio_i2c_readfrom_in
//| as if ``buffer[start:end]``. This will not cause an allocation like
//| ``buffer[start:end]`` will so it saves memory.
//|
//| Writing a buffer or slice of length zero is permitted, as it can be used
//| to poll for the existence of a device.
//|
//| :param int address: 7-bit device address
//| :param bytearray buffer: buffer containing the bytes to write
//| :param int start: Index to start writing from
@ -254,10 +258,6 @@ STATIC mp_obj_t busio_i2c_writeto(size_t n_args, const mp_obj_t *pos_args, mp_ma
uint32_t length = bufinfo.len;
normalize_buffer_bounds(&start, args[ARG_end].u_int, &length);
if (length == 0) {
mp_raise_ValueError("Buffer must be at least length 1");
}
// do the transfer
uint8_t status = common_hal_busio_i2c_write(self, args[ARG_address].u_int,
((uint8_t*) bufinfo.buf) + start, length, args[ARG_stop].u_bool);

2
shared-bindings/busio/SPI.c
View File

@ -207,6 +207,7 @@ MP_DEFINE_CONST_FUN_OBJ_1(busio_spi_unlock_obj, busio_spi_obj_unlock);
//| .. method:: SPI.write(buffer, \*, start=0, end=len(buffer))
//|
//| Write the data contained in ``buf``. Requires the SPI being locked.
//| At least one byte must be written.
//|
//| :param bytearray buffer: buffer containing the bytes to write
//| :param int start: Index to start writing from
@ -247,6 +248,7 @@ MP_DEFINE_CONST_FUN_OBJ_KW(busio_spi_write_obj, 2, busio_spi_write);
//| .. method:: SPI.readinto(buffer, \*, start=0, end=len(buffer), write_value=0)
//|
//| Read into the buffer specified by ``buf`` while writing zeroes. Requires the SPI being locked.
//| At least one byte must be read.
//|
//| :param bytearray buffer: buffer to write into
//| :param int start: Index to start writing at