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Implement UART hardware flow control on SAMD chips

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This commit is contained in:
George White 2022-05-25 21:34:06 +00:00
parent 38f91539dc
commit fb3077ccc2
2 changed files with 57 additions and 5 deletions
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60
ports/atmel-samd/common-hal/busio/UART.c
View File

@ -71,12 +71,16 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
uint8_t rx_pad = 255; // Unset pad
uint32_t tx_pinmux = 0;
uint8_t tx_pad = 255; // Unset pad
uint32_t rts_pinmux = 0;
uint32_t cts_pinmux = 0;
// Set state so the object is deinited to start.
self->rx_pin = NO_PIN;
self->tx_pin = NO_PIN;
self->rts_pin = NO_PIN;
self->cts_pin = NO_PIN;
if ((rts != NULL) || (cts != NULL) || (rs485_dir != NULL) || (rs485_invert)) {
if ((rs485_dir != NULL) || (rs485_invert)) {
mp_raise_NotImplementedError(translate("RS485"));
}
@ -84,6 +88,9 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
bool have_tx = tx != NULL;
bool have_rx = rx != NULL;
bool have_rts = rts != NULL;
bool have_cts = cts != NULL;
if (!have_tx && !have_rx) {
mp_raise_ValueError(translate("tx and rx cannot both be None"));
}
@ -122,6 +129,9 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
#endif
tx_pinmux = PINMUX(tx->number, (i == 0) ? MUX_C : MUX_D);
tx_pad = tx->sercom[i].pad;
if (have_cts) {
cts_pinmux = PINMUX(cts->number, (i == 0) ? MUX_C : MUX_D);
}
if (rx == NULL) {
sercom = potential_sercom;
break;
@ -134,6 +144,9 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
rx->sercom[j].pad != tx_pad) {
rx_pinmux = PINMUX(rx->number, (j == 0) ? MUX_C : MUX_D);
rx_pad = rx->sercom[j].pad;
if (have_rts) {
rts_pinmux = PINMUX(rts->number, (j == 0) ? MUX_C : MUX_D);
}
sercom = sercom_insts[rx->sercom[j].index];
sercom_index = rx->sercom[j].index;
break;
@ -193,21 +206,32 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
// Set pads computed for this SERCOM.
// TXPO:
// 0x0: TX pad 0; no RTS/CTS
// 0x1: TX pad 2; no RTS/CTS
// 0x2: TX pad 0; RTS: pad 2, CTS: pad 3 (not used by us right now)
// So divide by 2 to map pad to value.
// 0x1: resevered
// 0x2: TX pad 0; RTS: pad 2, CTS: pad 3
// 0x3: TX pad 0; RTS: pad 2; no CTS
// RXPO:
// 0x0: RX pad 0
// 0x1: RX pad 1
// 0x2: RX pad 2
// 0x3: RX pad 3
// Default to TXPO with no RTS/CTS
uint8_t computed_txpo = 0;
// If we have both CTS (with or without RTS), use second pinout
if (have_cts) {
computed_txpo = 2;
}
// If we have RTS only, use the third pinout
if (have_rts && !have_cts) {
computed_txpo = 3;
}
// Doing a group mask and set of the registers saves 60 bytes over setting the bitfields individually.
sercom->USART.CTRLA.reg &= ~(SERCOM_USART_CTRLA_TXPO_Msk |
SERCOM_USART_CTRLA_RXPO_Msk |
SERCOM_USART_CTRLA_FORM_Msk);
sercom->USART.CTRLA.reg |= SERCOM_USART_CTRLA_TXPO(tx_pad / 2) |
sercom->USART.CTRLA.reg |= SERCOM_USART_CTRLA_TXPO(computed_txpo) |
SERCOM_USART_CTRLA_RXPO(rx_pad) |
(parity == BUSIO_UART_PARITY_NONE ? 0 : SERCOM_USART_CTRLA_FORM(1));
@ -257,6 +281,26 @@ void common_hal_busio_uart_construct(busio_uart_obj_t *self,
self->rx_pin = NO_PIN;
}
if (have_rts) {
gpio_set_pin_direction(rts->number, GPIO_DIRECTION_OUT);
gpio_set_pin_pull_mode(rts->number, GPIO_PULL_OFF);
gpio_set_pin_function(rts->number, rts_pinmux);
self->rts_pin = rts->number;
claim_pin(rts);
} else {
self->rts_pin = NO_PIN;
}
if (have_cts) {
gpio_set_pin_direction(cts->number, GPIO_DIRECTION_IN);
gpio_set_pin_pull_mode(cts->number, GPIO_PULL_OFF);
gpio_set_pin_function(cts->number, cts_pinmux);
self->cts_pin = cts->number;
claim_pin(cts);
} else {
self->cts_pin = NO_PIN;
}
usart_async_enable(usart_desc_p);
}
@ -270,6 +314,8 @@ void common_hal_busio_uart_never_reset(busio_uart_obj_t *self) {
never_reset_sercom(hw);
never_reset_pin_number(self->rx_pin);
never_reset_pin_number(self->tx_pin);
never_reset_pin_number(self->rts_pin);
never_reset_pin_number(self->cts_pin);
}
}
return;
@ -289,8 +335,12 @@ void common_hal_busio_uart_deinit(busio_uart_obj_t *self) {
usart_async_deinit(usart_desc_p);
reset_pin_number(self->rx_pin);
reset_pin_number(self->tx_pin);
reset_pin_number(self->rts_pin);
reset_pin_number(self->cts_pin);
self->rx_pin = NO_PIN;
self->tx_pin = NO_PIN;
self->rts_pin = NO_PIN;
self->cts_pin = NO_PIN;
}
// Read characters.

2
ports/atmel-samd/common-hal/busio/UART.h
View File

@ -38,6 +38,8 @@ typedef struct {
struct usart_async_descriptor usart_desc;
uint8_t rx_pin;
uint8_t tx_pin;
int8_t rts_pin;
int8_t cts_pin;
uint8_t character_bits;
bool rx_error;
uint32_t baudrate;