kopia lustrzana https://github.com/espressif/esp-idf
Merge branch 'bugfix/soft_uart_send_dummy_byte_v5.1' into 'release/v5.1'
fix(peripheral_drivers/dedicated_gpio): Remove dummy byte from the emulate_uart_send routine (backport v5.1) See merge request espressif/esp-idf!28687pull/13572/head
commit
37e0e8ab53
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@ -65,6 +65,10 @@ esp_err_t soft_uart_del(soft_uart_port_t port);
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/**
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* @brief Send the given bytes on the software UART port.
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*
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* @note Since toggling fast GPIOs for the first time may be slow (~1us), the first byte may be corrupted.
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* If you are seeing this issue, prepend a dummy byte to the buffer to send when calling this
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* function for the first time.
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*
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* @param port Software UART port to send data on.
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* @param write_buffer Buffer containing the bytes to send on the buffer. Must not be NULL.
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* @param write_size Size of the write buffer. Must not be 0.
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@ -1,5 +1,5 @@
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/*
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* SPDX-FileCopyrightText: 2010-2022 Espressif Systems (Shanghai) CO LTD
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* SPDX-FileCopyrightText: 2010-2024 Espressif Systems (Shanghai) CO LTD
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*
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* SPDX-License-Identifier: CC0-1.0
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*/
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@ -33,11 +33,6 @@ emulate_uart_send:
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sll a2, t0, a2
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/* Save return address in a4 */
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mv a4, ra
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/* As UART is very time sensitive, we want each bit sent to be very precise in terms of duration.
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* The first toggle of the fast GPIO register may be slow, ~1us, so let's send a dummy byte here
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* before the actual UART emulation start, else the first byte sent would be corrupted.*/
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li t0, 0
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call uart_send_byte
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/* Reading the characters 4 by 4 would be much faster, but in our case, we don't need
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* the process to be fast as the bottleneck is the UART speed */
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uart_read_next:
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@ -1,5 +1,5 @@
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/*
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* SPDX-FileCopyrightText: 2010-2022 Espressif Systems (Shanghai) CO LTD
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* SPDX-FileCopyrightText: 2010-2024 Espressif Systems (Shanghai) CO LTD
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*
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* SPDX-License-Identifier: CC0-1.0
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*/
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@ -18,6 +18,7 @@ void app_main(void)
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esp_err_t ret = ESP_OK;
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uint8_t read_buffer[READ_COUNT] = { 0 };
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const uint8_t write_buffer[] = "Hello, world! This is a message.\r\n";
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uint8_t dummy = 0;
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soft_uart_port_t port = NULL;
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soft_uart_config_t config = {
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.tx_pin = CONFIG_EMULATE_UART_GPIO_TX,
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@ -29,6 +30,10 @@ void app_main(void)
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ret = soft_uart_new(&config, &port);
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ESP_GOTO_ON_ERROR(ret, error, EXAMPLE_TAG, "Error configuring software UART");
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/* Send a dummy byte as the software UART driver may corrupt the first byte */
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ret = soft_uart_send(port, &dummy, sizeof(uint8_t));
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ESP_GOTO_ON_ERROR(ret, error, EXAMPLE_TAG, "Error writing a dummy byte");
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/* Write few bytes to the UART */
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ret = soft_uart_send(port, write_buffer, sizeof(write_buffer));
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ESP_GOTO_ON_ERROR(ret, error, EXAMPLE_TAG, "Error writing to the software UART");
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