73 lines
1.5 KiB
C
73 lines
1.5 KiB
C
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/*
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* Copyright (c) 2019 Nordic Semiconductor ASA.
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <gpio.h>
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#include <uart.h>
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#include <device.h>
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#define RESET_PIN CONFIG_BOARD_NRF52840_GPIO_RESET_PIN
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/* Must be a pin from 17 to 23.
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* Only those can be connected to the nRF52840.
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*/
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BUILD_ASSERT_MSG(RESET_PIN > 16 && RESET_PIN < 24,
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"Selected pin is not connected to nRF52840");
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int bt_hci_transport_setup(struct device *h4)
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{
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int err;
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char c;
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struct device *port;
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port = device_get_binding(DT_GPIO_P0_DEV_NAME);
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if (!port) {
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return -EIO;
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}
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/* Pull the pin low before configuring it as output, to ensure that
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* it is driven to the correct level as soon as it is configured.
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*/
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err = gpio_pin_write(port, RESET_PIN, 0);
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if (err) {
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return err;
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}
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err = gpio_pin_configure(port, RESET_PIN, GPIO_DIR_OUT);
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if (err) {
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return err;
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}
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/* Reset the nRF52840 and let it wait until the pin is
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* pulled low again before running to main to ensure
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* that it won't send any data until the H4 device
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* is setup and ready to receive.
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*/
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err = gpio_pin_write(port, RESET_PIN, 1);
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if (err) {
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return err;
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}
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/* Wait for the nRF52840 peripheral to stop sending data.
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*
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* It is critical (!) to wait here, so that all bytes
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* on the lines are received and drained correctly.
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*/
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k_sleep(1);
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/* Drain bytes */
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while (uart_fifo_read(h4, &c, 1)) {
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continue;
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}
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/* We are ready, let the nRF52840 run to main */
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err = gpio_pin_write(port, RESET_PIN, 0);
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if (err) {
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return err;
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}
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return 0;
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}
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