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samd/machine_uart.c: Add full support for 9bit data. #15787

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Nov 18, 2024
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samd/machine_uart.c: Add full support for 9bit data. #15787

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84 changes: 73 additions & 11 deletions ports/samd/machine_uart.c
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Original file line number Diff line number Diff line change
Expand Up @@ -107,10 +107,17 @@ static const char *_parity_name[] = {"None", "", "0", "1"}; // Is defined as 0,

// take all bytes from the fifo and store them in the buffer
static void uart_drain_rx_fifo(machine_uart_obj_t *self, Sercom *uart) {
uint8_t bits = self->bits;
while (uart->USART.INTFLAG.bit.RXC != 0) {
if (ringbuf_free(&self->read_buffer) > 0) {
// get a byte from uart and put into the buffer
ringbuf_put(&(self->read_buffer), uart->USART.DATA.bit.DATA);
if (ringbuf_free(&self->read_buffer) >= (bits <= 8 ? 1 : 2)) {
// get a word from uart and put into the buffer
if (bits <= 8) {
ringbuf_put(&(self->read_buffer), uart->USART.DATA.bit.DATA);
} else {
uint16_t data = uart->USART.DATA.bit.DATA;
ringbuf_put(&(self->read_buffer), data);
ringbuf_put(&(self->read_buffer), data >> 8);
}
} else {
// if the buffer is full, disable the RX interrupt
// allowing RTS to come up. It will be re-enabled by the next read
Expand Down Expand Up @@ -150,7 +157,12 @@ void common_uart_irq_handler(int uart_id) {
#if MICROPY_HW_UART_TXBUF
// handle the outgoing data
if (ringbuf_avail(&self->write_buffer) > 0) {
uart->USART.DATA.bit.DATA = ringbuf_get(&self->write_buffer);
if (self->bits <= 8) {
uart->USART.DATA.bit.DATA = ringbuf_get(&self->write_buffer);
} else {
uart->USART.DATA.bit.DATA =
ringbuf_get(&self->write_buffer) | (ringbuf_get(&self->write_buffer) << 8);
}
} else {
#if MICROPY_PY_MACHINE_UART_IRQ
// Set the TXIDLE flag
Expand Down Expand Up @@ -274,6 +286,17 @@ void machine_uart_set_baudrate(mp_obj_t self_in, uint32_t baudrate) {

static void mp_machine_uart_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
machine_uart_obj_t *self = MP_OBJ_TO_PTR(self_in);
size_t rxbuf_len = self->read_buffer.size - 1;
#if MICROPY_HW_UART_TXBUF
size_t txbuf_len = self->write_buffer.size - 1;
#endif
if (self->bits > 8) {
rxbuf_len /= 2;
#if MICROPY_HW_UART_TXBUF
txbuf_len /= 2;
#endif
}

mp_printf(print, "UART(%u, baudrate=%u, bits=%u, parity=%s, stop=%u, "
"timeout=%u, timeout_char=%u, rxbuf=%d"
#if MICROPY_HW_UART_TXBUF
Expand All @@ -287,9 +310,9 @@ static void mp_machine_uart_print(const mp_print_t *print, mp_obj_t self_in, mp_
#endif
")",
self->id, self->baudrate, self->bits, _parity_name[self->parity],
self->stop + 1, self->timeout, self->timeout_char, self->read_buffer.size - 1
self->stop + 1, self->timeout, self->timeout_char, rxbuf_len
#if MICROPY_HW_UART_TXBUF
, self->write_buffer.size - 1
, txbuf_len
#endif
#if MICROPY_HW_UART_RTSCTS
, self->rts != 0xff ? pin_find_by_id(self->rts)->name : MP_QSTR_None
Expand Down Expand Up @@ -411,6 +434,14 @@ static void mp_machine_uart_init_helper(machine_uart_obj_t *self, size_t n_args,
}
}
#endif

// Double the buffer lengths for 9 bit transfer
if (self->bits > 8) {
rxbuf_len *= 2;
#if MICROPY_HW_UART_TXBUF
txbuf_len *= 2;
#endif
}
// Initialise the UART peripheral if any arguments given, or it was not initialised previously.
if (n_args > 0 || kw_args->used > 0 || self->new) {
self->new = false;
Expand Down Expand Up @@ -619,7 +650,12 @@ static mp_uint_t mp_machine_uart_read(mp_obj_t self_in, void *buf_in, mp_uint_t
uint64_t timeout_char = self->timeout_char;
uint8_t *dest = buf_in;

for (size_t i = 0; i < size; i++) {
// Check that size is even for 9 bit transfers.
if ((self->bits >= 9) && (size & 1)) {
*errcode = MP_EIO;
return MP_STREAM_ERROR;
}
for (size_t i = 0; i < size;) {
// Wait for the first/next character
while (ringbuf_avail(&self->read_buffer) == 0) {
if (mp_hal_ticks_ms_64() > t) { // timed out
Expand All @@ -633,6 +669,11 @@ static mp_uint_t mp_machine_uart_read(mp_obj_t self_in, void *buf_in, mp_uint_t
MICROPY_EVENT_POLL_HOOK
}
*dest++ = ringbuf_get(&(self->read_buffer));
i++;
if (self->bits >= 9 && i < size) {
*dest++ = ringbuf_get(&(self->read_buffer));
i++;
}
t = mp_hal_ticks_ms_64() + timeout_char;
// (Re-)Enable RXC interrupt
if ((uart->USART.INTENSET.reg & SERCOM_USART_INTENSET_RXC) == 0) {
Expand All @@ -647,12 +688,19 @@ static mp_uint_t mp_machine_uart_write(mp_obj_t self_in, const void *buf_in, mp_
size_t i = 0;
const uint8_t *src = buf_in;
Sercom *uart = sercom_instance[self->id];

uint64_t t = mp_hal_ticks_ms_64() + self->timeout;
uint8_t bits = self->bits;
// Check that size is even for 9 bit transfers.
if ((bits >= 9) && (size & 1)) {
*errcode = MP_EIO;
return MP_STREAM_ERROR;
}

#if MICROPY_HW_UART_TXBUF

#if MICROPY_PY_MACHINE_UART_IRQ
// Prefill the FIFO to get rid of the initial IRQ_TXIDLE event
// Do not care for 9 Bit transfer here since the UART is not yet started.
while (i < size && ringbuf_free(&(self->write_buffer)) > 0) {
ringbuf_put(&(self->write_buffer), *src++);
i++;
Expand All @@ -672,8 +720,16 @@ static mp_uint_t mp_machine_uart_write(mp_obj_t self_in, const void *buf_in, mp_
}
MICROPY_EVENT_POLL_HOOK
}
ringbuf_put(&(self->write_buffer), *src++);
i++;
if (bits >= 9) {
mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION();
ringbuf_put(&(self->write_buffer), *src++);
ringbuf_put(&(self->write_buffer), *src++);
i += 2;
MICROPY_END_ATOMIC_SECTION(atomic_state);
} else {
ringbuf_put(&(self->write_buffer), *src++);
i += 1;
}
uart->USART.INTENSET.reg = SERCOM_USART_INTENSET_DRE; // kick off the IRQ
}

Expand All @@ -691,7 +747,13 @@ static mp_uint_t mp_machine_uart_write(mp_obj_t self_in, const void *buf_in, mp_
}
MICROPY_EVENT_POLL_HOOK
}
uart->USART.DATA.bit.DATA = *src++;
if (self->bits > 8 && i < (size - 1)) {
uart->USART.DATA.bit.DATA = *(uint16_t *)src;
i++;
src += 2;
} else {
uart->USART.DATA.bit.DATA = *src++;
}
i++;
}
#endif
Expand Down
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