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Merge pull request #713 from ourairquality/tsoftuart
tsoftuart: add a softare timer base UART driver, and example.
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!local.mk |
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#define configUSE_TRACE_FACILITY 1 | ||
#define configGENERATE_RUN_TIME_STATS 1 | ||
#define portGET_RUN_TIME_COUNTER_VALUE() (RTC.COUNTER) | ||
#define portCONFIGURE_TIMER_FOR_RUN_TIME_STATS() {} | ||
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/* Use the defaults for everything else */ | ||
#include_next<FreeRTOSConfig.h> |
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# Makefile for tsfotuart example | ||
PROGRAM=tsoftuart | ||
EXTRA_COMPONENTS=extras/dhcpserver extras/wificfg extras/mactimer extras/tsoftuart | ||
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# For the mDNS responder included with lwip: | ||
EXTRA_CFLAGS += -DLWIP_MDNS_RESPONDER=1 -DLWIP_NUM_NETIF_CLIENT_DATA=1 -DLWIP_NETIF_EXT_STATUS_CALLBACK=1 | ||
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# Avoid writing the wifi state to flash when using wificfg. | ||
EXTRA_CFLAGS += -DWIFI_PARAM_SAVE=0 | ||
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EXTRA_CFLAGS += -DWIFICFG_CLIENT_TASK=1 -DWIFICFG_IRAM_TEST=1 | ||
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include ../../common.mk |
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FLASH_SIZE ?= 32 |
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/* | ||
* Example timer based software UART drive. | ||
* | ||
* Copyright (C) 2019 OurAirQuality.org | ||
* | ||
* Licensed under the Apache License, Version 2.0, January 2004 (the | ||
* "License"); you may not use this file except in compliance with the | ||
* License. You may obtain a copy of the License at | ||
* http://www.apache.org/licenses/ | ||
* | ||
* 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 CONTRIBUTORS 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 WITH THE SOFTWARE. | ||
* | ||
*/ | ||
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#include <string.h> | ||
#include <ctype.h> | ||
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#include <espressif/esp_common.h> | ||
#include <espressif/user_interface.h> | ||
#include <esp/uart.h> | ||
#include <FreeRTOS.h> | ||
#include <task.h> | ||
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#include "lwip/sockets.h" | ||
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#include "wificfg/wificfg.h" | ||
#include "tsoftuart/tsoftuart.h" | ||
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static void tsoftuart_task(void *pvParameters) | ||
{ | ||
/* Initialize the UART Tx. */ | ||
uint32_t tx_pin = *(uint32_t *)pvParameters; | ||
struct tsoftuart *uart = tsoftuart_init(tx_pin, 9600); | ||
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for (;;) { | ||
/* Reset the timing error records. */ | ||
uart->output_queue_error_low = 0; | ||
uart->output_queue_error_high = 0; | ||
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char str[] = "Hello 0123456789 abcdefghijklmnopqrstuvwxyz\r\n"; | ||
for (size_t i = 0; i < strlen(str); i++) { | ||
tsoftuart_putc(uart, str[i]); | ||
} | ||
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/* Check the timing error. */ | ||
if (uart->output_queue_error_high > 2 || uart->output_queue_error_low < -2) { | ||
tsoftuart_write(uart, "X\r\n", 3); | ||
} | ||
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vTaskDelay(200 / portTICK_PERIOD_MS); | ||
} | ||
} | ||
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void user_init(void) | ||
{ | ||
uart_set_baud(0, 115200); | ||
printf("SDK version:%s\n", sdk_system_get_sdk_version()); | ||
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wificfg_init(80, NULL); | ||
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/* Start two tasks writing to different pins. */ | ||
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static uint32_t tx_pin1 = 1; | ||
xTaskCreate(&tsoftuart_task, "tsoftuart1", 256, &tx_pin1, 1, NULL); | ||
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static uint32_t tx_pin2 = 2; | ||
xTaskCreate(&tsoftuart_task, "tsoftuart2", 256, &tx_pin2, 1, NULL); | ||
} |
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# Component makefile for extras/tsoftuart | ||
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# Expected anyone using tsoftuart includes it as 'tsoftuart/tsoftuart.h' | ||
INC_DIRS += $(tsoftuart_ROOT).. | ||
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# args for passing into compile rule generation | ||
tsoftuart_INC_DIR = | ||
tsoftuart_SRC_DIR = $(tsoftuart_ROOT) | ||
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$(eval $(call component_compile_rules,tsoftuart)) |
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/* | ||
* Software timer based UART driver. | ||
* | ||
* Copyright (C) 2018 to 2019 OurAirQuality.org | ||
* | ||
* Licensed under the Apache License, Version 2.0, January 2004 (the | ||
* "License"); you may not use this file except in compliance with the | ||
* License. You may obtain a copy of the License at | ||
* http://www.apache.org/licenses/ | ||
* | ||
* 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 CONTRIBUTORS 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 WITH THE SOFTWARE. | ||
* | ||
*/ | ||
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#include <stdint.h> | ||
#include <sys/types.h> | ||
#include <stdlib.h> | ||
#include <unistd.h> | ||
#include <esp/uart.h> | ||
#include <stdio.h> | ||
#include <espressif/esp_system.h> | ||
#include "FreeRTOS.h" | ||
#include "task.h" | ||
#include "tsoftuart/tsoftuart.h" | ||
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/* | ||
* The design builds a sequence of UART output transitions - the delay between | ||
* each toggling of the output. This sequence is then followed by a timer and | ||
* the timer handler toggles the state and resets the timer for the next | ||
* transition until done. This design avoids the code having to spin to | ||
* implement delays, and avoid having to disable interrupts for more reliable | ||
* timing. | ||
* | ||
* The MAC timer interrupt is used here as it has a high priority which helps | ||
* keep accurate output transition times. The MAC timer interrupt is a NMI and | ||
* the handler needs to take care not to interact widely. The handler only | ||
* accesses the timer queue, which has already been initialized. | ||
* | ||
* This software UART is not completely reliable, but might suit debug output | ||
* or communication that has an error detection layer, and it is more reliable | ||
* at lower baud rates. While it can run up to 115200 baud it is not very | ||
* reliable at these higher rates. It is not uncommon for the MAC timer | ||
* handler to be delayed 20us, so at UART baud rates above 19200 errors are | ||
* expected. This driver attempts to measure the timing errors and this can be | ||
* used to help detect when timing errors have occurred. | ||
*/ | ||
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static void IRAM output_handler(void *arg) | ||
{ | ||
tsoftuart_t *uart = arg; | ||
uint32_t tail = uart->output_queue_tail; | ||
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do { | ||
uint32_t state = uart->output_queue_state ^ 1; | ||
uint64_t current = mactime_get_count(); | ||
gpio_write(uart->tx_pin, state); | ||
uart->output_queue_state = state; | ||
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if (tail == 0) { | ||
// First transition. | ||
uart->output_start_time = current; | ||
uart->output_expected_time = current; | ||
} | ||
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/* The difference can be negative because the delay is skipped | ||
* if very short, see below. */ | ||
int32_t err = current - uart->output_expected_time; | ||
if (err > uart->output_queue_error_high) { | ||
uart->output_queue_error_high = err; | ||
} | ||
if (err < uart->output_queue_error_low) { | ||
uart->output_queue_error_low = err; | ||
} | ||
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if (tail >= uart->output_queue_head) { | ||
// Done. | ||
uart->output_queue_tail = tail; | ||
uart->output_done = 1; | ||
return; | ||
} | ||
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/* Offset from the start. */ | ||
uint32_t next = uart->output_queue[tail++]; | ||
uint64_t target = uart->output_start_time + next; | ||
uart->output_expected_time = target; | ||
/* Target an earlier time, that would not give an error if | ||
* actually met, to give more room for the response delay. */ | ||
target -= 4; | ||
int64_t diff = target - current; | ||
if (diff >= 0) { | ||
uart->output_queue_tail = tail; | ||
mactime_add_pending(&uart->output_mactimer, target); | ||
break; | ||
} | ||
} while(1); | ||
} | ||
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void tsoftuart_putc(tsoftuart_t *uart, uint8_t ch) | ||
{ | ||
uart->output_queue_state = 1; | ||
gpio_write(uart->tx_pin, uart->output_queue_state); | ||
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uart->output_queue_head = 0; | ||
uart->output_queue_tail = 0; | ||
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uart->output_queue_error_high = 0; | ||
uart->output_queue_error_low = 0; | ||
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uart->output_done = 0; | ||
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uint32_t state = 0; | ||
uint32_t count = 1; | ||
size_t head = 0; | ||
uint32_t cumulative = 0; | ||
uint32_t td = uart->td; | ||
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for (size_t i = 0; i < 8; i++) { | ||
if ((ch & 1) == state) { | ||
/* No change */ | ||
count++; | ||
} else { | ||
cumulative += count * td; | ||
uart->output_queue[head++] = (cumulative + 128) >> 8; | ||
state ^= 1; | ||
count = 1; | ||
} | ||
ch >>= 1; | ||
} | ||
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if (state == 0) { | ||
cumulative += count * td; | ||
uart->output_queue[head++] = (cumulative + 128) >> 8; | ||
state ^= 1; | ||
count = 1; | ||
} | ||
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uart->output_queue_head = head; | ||
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/* Trigger the first transition in the future. */ | ||
mactimer_arm(&uart->output_mactimer, 20); | ||
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/* Wait until the transmittions is expected to have completed. */ | ||
uint32_t delay = (td * 11 + 128) >> 8; | ||
vTaskDelay(((delay / 1000) + portTICK_PERIOD_MS) / portTICK_PERIOD_MS); | ||
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/* Double check that it is done. There is a possibility that the timer has | ||
* failed to trigger, and this needed to be detected and the timer removed | ||
* from the pending list before retrying. */ | ||
size_t i; | ||
for (i = 0; uart->output_done == 0 && i < 10; i++) { | ||
vTaskDelay(1); | ||
} | ||
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if (uart->output_done == 0) { | ||
/* Remove the timer. */ | ||
mactimer_disarm(&uart->output_mactimer); | ||
/* Set the output high */ | ||
gpio_write(uart->tx_pin, 1); | ||
} | ||
} | ||
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ssize_t tsoftuart_write(tsoftuart_t *uart, const void *ptr, size_t len) | ||
{ | ||
for(int i = 0; i < len; i++) { | ||
tsoftuart_putc(uart, ((char *)ptr)[i]); | ||
} | ||
return len; | ||
} | ||
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tsoftuart_t *tsoftuart_init(uint8_t tx_pin, uint32_t baud_rate) | ||
{ | ||
tsoftuart_t *uart = malloc(sizeof(tsoftuart_t)); | ||
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if (uart) { | ||
uart->tx_pin = tx_pin; | ||
uart->td = 256000000 / baud_rate; | ||
gpio_enable(tx_pin, GPIO_OUTPUT); | ||
gpio_set_pullup(tx_pin, true, false); | ||
gpio_write(tx_pin, 1); | ||
mactimer_init(); | ||
mactimer_setfn(&uart->output_mactimer, output_handler, uart); | ||
} | ||
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return uart; | ||
} | ||
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/* | ||
* Software timer based UART driver. | ||
* | ||
* Copyright (C) 2018 to 2019 OurAirQuality.org | ||
* | ||
* Licensed under the Apache License, Version 2.0, January 2004 (the | ||
* "License"); you may not use this file except in compliance with the | ||
* License. You may obtain a copy of the License at | ||
* http://www.apache.org/licenses/ | ||
* | ||
* 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 CONTRIBUTORS 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 WITH THE SOFTWARE. | ||
* | ||
*/ | ||
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#ifndef _TSOFTUART_H | ||
#define _TSOFTUART_H | ||
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#include "mactimer/mactimer.h" | ||
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typedef struct tsoftuart { | ||
uint32_t tx_pin; | ||
/* Bit time period in usec * 256 */ | ||
uint32_t td; | ||
mactimer_t output_mactimer; | ||
uint32_t output_queue[16]; | ||
volatile uint64_t output_start_time; | ||
volatile size_t output_queue_head; | ||
volatile size_t output_queue_tail; | ||
size_t output_queue_state; | ||
uint64_t output_expected_time; | ||
int32_t output_queue_error_high; | ||
int32_t output_queue_error_low; | ||
uint32_t output_done; | ||
} tsoftuart_t; | ||
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void tsoftuart_putc(tsoftuart_t *uart, uint8_t ch); | ||
ssize_t tsoftuart_write(tsoftuart_t *uart, const void *ptr, size_t len); | ||
tsoftuart_t *tsoftuart_init(uint8_t tx_pin, uint32_t baud_rate); | ||
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#endif /* _TSOFTUART_H */ |