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circuitpython/ports/esp32/machine_uart.c
Will Sowerbutts a3675294ae esp32/machine_uart: Add flow kw-arg to enable hardware flow control. 
This enables optional support for the hardware UART to use the RTS and/or
CTS pins for flow control.

The new "flow" constructor keyword specifies a bitmask of RTS and/or CTS.
This matches the interface used by machine.UART on stm32 and rp2.

Previously on ESP32 it was possible to specify which pins to use for the
RTS and CTS signals, but hardware flow control was never functional: CTS
was not checked before transmitting bytes, and RTS was always driven high
(signalling no buffer space available).  With this patch, CTS and RTS both
operate as expected.

This also includes an update to the machine.UART documentation.

Signed-off-by: Will Sowerbutts <will@sowerbutts.com>
2021-08-04 13:52:15 +10:00

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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2016 Damien P. George
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include "driver/uart.h"
#include "freertos/FreeRTOS.h"
#include "py/runtime.h"
#include "py/stream.h"
#include "py/mperrno.h"
#include "modmachine.h"
#if ESP_IDF_VERSION < ESP_IDF_VERSION_VAL(4, 1, 0)
#define UART_INV_TX UART_INVERSE_TXD
#define UART_INV_RX UART_INVERSE_RXD
#define UART_INV_RTS UART_INVERSE_RTS
#define UART_INV_CTS UART_INVERSE_CTS
#else
#define UART_INV_TX UART_SIGNAL_TXD_INV
#define UART_INV_RX UART_SIGNAL_RXD_INV
#define UART_INV_RTS UART_SIGNAL_RTS_INV
#define UART_INV_CTS UART_SIGNAL_CTS_INV
#endif
#define UART_INV_MASK (UART_INV_TX | UART_INV_RX | UART_INV_RTS | UART_INV_CTS)
typedef struct _machine_uart_obj_t {
mp_obj_base_t base;
uart_port_t uart_num;
uart_hw_flowcontrol_t flowcontrol;
uint8_t bits;
uint8_t parity;
uint8_t stop;
int8_t tx;
int8_t rx;
int8_t rts;
int8_t cts;
uint16_t txbuf;
uint16_t rxbuf;
uint16_t timeout; // timeout waiting for first char (in ms)
uint16_t timeout_char; // timeout waiting between chars (in ms)
uint32_t invert; // lines to invert
} machine_uart_obj_t;
STATIC const char *_parity_name[] = {"None", "1", "0"};
/******************************************************************************/
// MicroPython bindings for UART
STATIC void 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);
uint32_t baudrate;
uart_get_baudrate(self->uart_num, &baudrate);
mp_printf(print, "UART(%u, baudrate=%u, bits=%u, parity=%s, stop=%u, tx=%d, rx=%d, rts=%d, cts=%d, txbuf=%u, rxbuf=%u, timeout=%u, timeout_char=%u",
self->uart_num, baudrate, self->bits, _parity_name[self->parity],
self->stop, self->tx, self->rx, self->rts, self->cts, self->txbuf, self->rxbuf, self->timeout, self->timeout_char);
if (self->invert) {
mp_printf(print, ", invert=");
uint32_t invert_mask = self->invert;
if (invert_mask & UART_INV_TX) {
mp_printf(print, "INV_TX");
invert_mask &= ~UART_INV_TX;
if (invert_mask) {
mp_printf(print, "|");
}
}
if (invert_mask & UART_INV_RX) {
mp_printf(print, "INV_RX");
invert_mask &= ~UART_INV_RX;
if (invert_mask) {
mp_printf(print, "|");
}
}
if (invert_mask & UART_INV_RTS) {
mp_printf(print, "INV_RTS");
invert_mask &= ~UART_INV_RTS;
if (invert_mask) {
mp_printf(print, "|");
}
}
if (invert_mask & UART_INV_CTS) {
mp_printf(print, "INV_CTS");
}
}
if (self->flowcontrol) {
mp_printf(print, ", flow=");
uint32_t flow_mask = self->flowcontrol;
if (flow_mask & UART_HW_FLOWCTRL_RTS) {
mp_printf(print, "RTS");
flow_mask &= ~UART_HW_FLOWCTRL_RTS;
if (flow_mask) {
mp_printf(print, "|");
}
}
if (flow_mask & UART_HW_FLOWCTRL_CTS) {
mp_printf(print, "CTS");
}
}
mp_printf(print, ")");
}
STATIC void machine_uart_init_helper(machine_uart_obj_t *self, size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
enum { ARG_baudrate, ARG_bits, ARG_parity, ARG_stop, ARG_tx, ARG_rx, ARG_rts, ARG_cts, ARG_txbuf, ARG_rxbuf, ARG_timeout, ARG_timeout_char, ARG_invert, ARG_flow };
static const mp_arg_t allowed_args[] = {
{ MP_QSTR_baudrate, MP_ARG_INT, {.u_int = 0} },
{ MP_QSTR_bits, MP_ARG_INT, {.u_int = 0} },
{ MP_QSTR_parity, MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
{ MP_QSTR_stop, MP_ARG_INT, {.u_int = 0} },
{ MP_QSTR_tx, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = UART_PIN_NO_CHANGE} },
{ MP_QSTR_rx, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = UART_PIN_NO_CHANGE} },
{ MP_QSTR_rts, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = UART_PIN_NO_CHANGE} },
{ MP_QSTR_cts, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = UART_PIN_NO_CHANGE} },
{ MP_QSTR_txbuf, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
{ MP_QSTR_rxbuf, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = -1} },
{ MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
{ MP_QSTR_timeout_char, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
{ MP_QSTR_invert, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
{ MP_QSTR_flow, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
};
mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
// wait for all data to be transmitted before changing settings
uart_wait_tx_done(self->uart_num, pdMS_TO_TICKS(1000));
if (args[ARG_txbuf].u_int >= 0 || args[ARG_rxbuf].u_int >= 0) {
// must reinitialise driver to change the tx/rx buffer size
if (args[ARG_txbuf].u_int >= 0) {
self->txbuf = args[ARG_txbuf].u_int;
}
if (args[ARG_rxbuf].u_int >= 0) {
self->rxbuf = args[ARG_rxbuf].u_int;
}
uart_config_t uartcfg = {
.flow_ctrl = UART_HW_FLOWCTRL_DISABLE,
.rx_flow_ctrl_thresh = 0
};
uint32_t baudrate;
uart_get_baudrate(self->uart_num, &baudrate);
uartcfg.baud_rate = baudrate;
uart_get_word_length(self->uart_num, &uartcfg.data_bits);
uart_get_parity(self->uart_num, &uartcfg.parity);
uart_get_stop_bits(self->uart_num, &uartcfg.stop_bits);
uart_driver_delete(self->uart_num);
uart_param_config(self->uart_num, &uartcfg);
uart_driver_install(self->uart_num, self->rxbuf, self->txbuf, 0, NULL, 0);
}
// set baudrate
uint32_t baudrate = 115200;
if (args[ARG_baudrate].u_int > 0) {
uart_set_baudrate(self->uart_num, args[ARG_baudrate].u_int);
uart_get_baudrate(self->uart_num, &baudrate);
}
uart_set_pin(self->uart_num, args[ARG_tx].u_int, args[ARG_rx].u_int, args[ARG_rts].u_int, args[ARG_cts].u_int);
if (args[ARG_tx].u_int != UART_PIN_NO_CHANGE) {
self->tx = args[ARG_tx].u_int;
}
if (args[ARG_rx].u_int != UART_PIN_NO_CHANGE) {
self->rx = args[ARG_rx].u_int;
}
if (args[ARG_rts].u_int != UART_PIN_NO_CHANGE) {
self->rts = args[ARG_rts].u_int;
}
if (args[ARG_cts].u_int != UART_PIN_NO_CHANGE) {
self->cts = args[ARG_cts].u_int;
}
// set data bits
switch (args[ARG_bits].u_int) {
case 0:
break;
case 5:
uart_set_word_length(self->uart_num, UART_DATA_5_BITS);
self->bits = 5;
break;
case 6:
uart_set_word_length(self->uart_num, UART_DATA_6_BITS);
self->bits = 6;
break;
case 7:
uart_set_word_length(self->uart_num, UART_DATA_7_BITS);
self->bits = 7;
break;
case 8:
uart_set_word_length(self->uart_num, UART_DATA_8_BITS);
self->bits = 8;
break;
default:
mp_raise_ValueError(MP_ERROR_TEXT("invalid data bits"));
break;
}
// set parity
if (args[ARG_parity].u_obj != MP_OBJ_NULL) {
if (args[ARG_parity].u_obj == mp_const_none) {
uart_set_parity(self->uart_num, UART_PARITY_DISABLE);
self->parity = 0;
} else {
mp_int_t parity = mp_obj_get_int(args[ARG_parity].u_obj);
if (parity & 1) {
uart_set_parity(self->uart_num, UART_PARITY_ODD);
self->parity = 1;
} else {
uart_set_parity(self->uart_num, UART_PARITY_EVEN);
self->parity = 2;
}
}
}
// set stop bits
switch (args[ARG_stop].u_int) {
// FIXME: ESP32 also supports 1.5 stop bits
case 0:
break;
case 1:
uart_set_stop_bits(self->uart_num, UART_STOP_BITS_1);
self->stop = 1;
break;
case 2:
uart_set_stop_bits(self->uart_num, UART_STOP_BITS_2);
self->stop = 2;
break;
default:
mp_raise_ValueError(MP_ERROR_TEXT("invalid stop bits"));
break;
}
// set timeout
self->timeout = args[ARG_timeout].u_int;
// set timeout_char
// make sure it is at least as long as a whole character (13 bits to be safe)
self->timeout_char = args[ARG_timeout_char].u_int;
uint32_t min_timeout_char = 13000 / baudrate + 1;
if (self->timeout_char < min_timeout_char) {
self->timeout_char = min_timeout_char;
}
// set line inversion
if (args[ARG_invert].u_int & ~UART_INV_MASK) {
mp_raise_ValueError(MP_ERROR_TEXT("invalid inversion mask"));
}
self->invert = args[ARG_invert].u_int;
uart_set_line_inverse(self->uart_num, self->invert);
// set hardware flow control
if (args[ARG_flow].u_int & ~UART_HW_FLOWCTRL_CTS_RTS) {
mp_raise_ValueError(MP_ERROR_TEXT("invalid flow control mask"));
}
self->flowcontrol = args[ARG_flow].u_int;
uart_set_hw_flow_ctrl(self->uart_num, self->flowcontrol, UART_FIFO_LEN - UART_FIFO_LEN / 4);
}
STATIC mp_obj_t machine_uart_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
mp_arg_check_num(n_args, n_kw, 1, MP_OBJ_FUN_ARGS_MAX, true);
// get uart id
mp_int_t uart_num = mp_obj_get_int(args[0]);
if (uart_num < 0 || uart_num >= UART_NUM_MAX) {
mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("UART(%d) does not exist"), uart_num);
}
// Attempts to use UART0 from Python has resulted in all sorts of fun errors.
// FIXME: UART0 is disabled for now.
if (uart_num == UART_NUM_0) {
mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("UART(%d) is disabled (dedicated to REPL)"), uart_num);
}
// Defaults
uart_config_t uartcfg = {
.baud_rate = 115200,
.data_bits = UART_DATA_8_BITS,
.parity = UART_PARITY_DISABLE,
.stop_bits = UART_STOP_BITS_1,
.flow_ctrl = UART_HW_FLOWCTRL_DISABLE,
.rx_flow_ctrl_thresh = 0
};
// create instance
machine_uart_obj_t *self = m_new_obj(machine_uart_obj_t);
self->base.type = &machine_uart_type;
self->uart_num = uart_num;
self->bits = 8;
self->parity = 0;
self->stop = 1;
self->rts = UART_PIN_NO_CHANGE;
self->cts = UART_PIN_NO_CHANGE;
self->txbuf = 256;
self->rxbuf = 256; // IDF minimum
self->timeout = 0;
self->timeout_char = 0;
switch (uart_num) {
case UART_NUM_0:
self->rx = UART_PIN_NO_CHANGE; // GPIO 3
self->tx = UART_PIN_NO_CHANGE; // GPIO 1
break;
case UART_NUM_1:
self->rx = 9;
self->tx = 10;
break;
#if SOC_UART_NUM > 2
case UART_NUM_2:
self->rx = 16;
self->tx = 17;
break;
#endif
}
// Remove any existing configuration
uart_driver_delete(self->uart_num);
// init the peripheral
// Setup
uart_param_config(self->uart_num, &uartcfg);
uart_driver_install(uart_num, self->rxbuf, self->txbuf, 0, NULL, 0);
mp_map_t kw_args;
mp_map_init_fixed_table(&kw_args, n_kw, args + n_args);
machine_uart_init_helper(self, n_args - 1, args + 1, &kw_args);
// Make sure pins are connected.
uart_set_pin(self->uart_num, self->tx, self->rx, self->rts, self->cts);
return MP_OBJ_FROM_PTR(self);
}
STATIC mp_obj_t machine_uart_init(size_t n_args, const mp_obj_t *args, mp_map_t *kw_args) {
machine_uart_init_helper(args[0], n_args - 1, args + 1, kw_args);
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_KW(machine_uart_init_obj, 1, machine_uart_init);
STATIC mp_obj_t machine_uart_deinit(mp_obj_t self_in) {
machine_uart_obj_t *self = MP_OBJ_TO_PTR(self_in);
uart_driver_delete(self->uart_num);
return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_uart_deinit_obj, machine_uart_deinit);
STATIC mp_obj_t machine_uart_any(mp_obj_t self_in) {
machine_uart_obj_t *self = MP_OBJ_TO_PTR(self_in);
size_t rxbufsize;
uart_get_buffered_data_len(self->uart_num, &rxbufsize);
return MP_OBJ_NEW_SMALL_INT(rxbufsize);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_uart_any_obj, machine_uart_any);
STATIC mp_obj_t machine_uart_sendbreak(mp_obj_t self_in) {
machine_uart_obj_t *self = MP_OBJ_TO_PTR(self_in);
// Save settings
uart_word_length_t word_length;
uart_parity_t parity;
uart_get_word_length(self->uart_num, &word_length);
uart_get_parity(self->uart_num, &parity);
// Synthesise the break condition by either a longer word or using even parity
uart_wait_tx_done(self->uart_num, pdMS_TO_TICKS(1000));
if (word_length != UART_DATA_8_BITS) {
uart_set_word_length(self->uart_num, UART_DATA_8_BITS);
} else if (parity == UART_PARITY_DISABLE) {
uart_set_parity(self->uart_num, UART_PARITY_EVEN);
} else {
// Cannot synthesise break
mp_raise_OSError(MP_EPERM);
}
char buf[1] = {0};
uart_write_bytes(self->uart_num, buf, 1);
uart_wait_tx_done(self->uart_num, pdMS_TO_TICKS(1000));
// Restore original settings
uart_set_word_length(self->uart_num, word_length);
uart_set_parity(self->uart_num, parity);
return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_uart_sendbreak_obj, machine_uart_sendbreak);
STATIC const mp_rom_map_elem_t machine_uart_locals_dict_table[] = {
{ MP_ROM_QSTR(MP_QSTR_init), MP_ROM_PTR(&machine_uart_init_obj) },
{ MP_ROM_QSTR(MP_QSTR_deinit), MP_ROM_PTR(&machine_uart_deinit_obj) },
{ MP_ROM_QSTR(MP_QSTR_any), MP_ROM_PTR(&machine_uart_any_obj) },
{ MP_ROM_QSTR(MP_QSTR_read), MP_ROM_PTR(&mp_stream_read_obj) },
{ MP_ROM_QSTR(MP_QSTR_readline), MP_ROM_PTR(&mp_stream_unbuffered_readline_obj) },
{ MP_ROM_QSTR(MP_QSTR_readinto), MP_ROM_PTR(&mp_stream_readinto_obj) },
{ MP_ROM_QSTR(MP_QSTR_write), MP_ROM_PTR(&mp_stream_write_obj) },
{ MP_ROM_QSTR(MP_QSTR_sendbreak), MP_ROM_PTR(&machine_uart_sendbreak_obj) },
{ MP_ROM_QSTR(MP_QSTR_INV_TX), MP_ROM_INT(UART_INV_TX) },
{ MP_ROM_QSTR(MP_QSTR_INV_RX), MP_ROM_INT(UART_INV_RX) },
{ MP_ROM_QSTR(MP_QSTR_INV_RTS), MP_ROM_INT(UART_INV_RTS) },
{ MP_ROM_QSTR(MP_QSTR_INV_CTS), MP_ROM_INT(UART_INV_CTS) },
{ MP_ROM_QSTR(MP_QSTR_RTS), MP_ROM_INT(UART_HW_FLOWCTRL_RTS) },
{ MP_ROM_QSTR(MP_QSTR_CTS), MP_ROM_INT(UART_HW_FLOWCTRL_CTS) },
};
STATIC MP_DEFINE_CONST_DICT(machine_uart_locals_dict, machine_uart_locals_dict_table);
STATIC mp_uint_t machine_uart_read(mp_obj_t self_in, void *buf_in, mp_uint_t size, int *errcode) {
machine_uart_obj_t *self = MP_OBJ_TO_PTR(self_in);
// make sure we want at least 1 char
if (size == 0) {
return 0;
}
TickType_t time_to_wait;
if (self->timeout == 0) {
time_to_wait = 0;
} else {
time_to_wait = pdMS_TO_TICKS(self->timeout);
}
int bytes_read = uart_read_bytes(self->uart_num, buf_in, size, time_to_wait);
if (bytes_read <= 0) {
*errcode = MP_EAGAIN;
return MP_STREAM_ERROR;
}
return bytes_read;
}
STATIC mp_uint_t machine_uart_write(mp_obj_t self_in, const void *buf_in, mp_uint_t size, int *errcode) {
machine_uart_obj_t *self = MP_OBJ_TO_PTR(self_in);
int bytes_written = uart_write_bytes(self->uart_num, buf_in, size);
if (bytes_written < 0) {
*errcode = MP_EAGAIN;
return MP_STREAM_ERROR;
}
// return number of bytes written
return bytes_written;
}
STATIC mp_uint_t machine_uart_ioctl(mp_obj_t self_in, mp_uint_t request, uintptr_t arg, int *errcode) {
machine_uart_obj_t *self = self_in;
mp_uint_t ret;
if (request == MP_STREAM_POLL) {
mp_uint_t flags = arg;
ret = 0;
size_t rxbufsize;
uart_get_buffered_data_len(self->uart_num, &rxbufsize);
if ((flags & MP_STREAM_POLL_RD) && rxbufsize > 0) {
ret |= MP_STREAM_POLL_RD;
}
if ((flags & MP_STREAM_POLL_WR) && 1) { // FIXME: uart_tx_any_room(self->uart_num)
ret |= MP_STREAM_POLL_WR;
}
} else {
*errcode = MP_EINVAL;
ret = MP_STREAM_ERROR;
}
return ret;
}
STATIC const mp_stream_p_t uart_stream_p = {
.read = machine_uart_read,
.write = machine_uart_write,
.ioctl = machine_uart_ioctl,
.is_text = false,
};
const mp_obj_type_t machine_uart_type = {
{ &mp_type_type },
.name = MP_QSTR_UART,
.print = machine_uart_print,
.make_new = machine_uart_make_new,
.getiter = mp_identity_getiter,
.iternext = mp_stream_unbuffered_iter,
.protocol = &uart_stream_p,
.locals_dict = (mp_obj_dict_t *)&machine_uart_locals_dict,
};
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