Use UART, but make the TX pin open drain.

Question

It is possible to switch the TX pin to open drain, when the UART is enabled on an nrf53? 
 My goal is to use the uart as a 1 wire interface,

hmolesworth · Accepted Answer

A couple of more links; note you might be able to spoof 1-wire with 3-wire SPI., don't remember if I tried that 
 dht22-sensor 
 1-wire-code-problem 
 3-wire-spi-bi-directional

Jordan Archer · Answer

You missed the original question. Can I make the uart device, with the TX pin being open drain?

hmolesworth · Answer

I edited my response above to show input connected; assuming you are wanting to use a single pin for both Tx and Rx. Let us know if you have it working ok - thanks

hmolesworth · Answer

Ah, I see. Try adding this function in SDKv1.5.1 uart_nrfx_uarte.c : 
 NRF_STATIC_INLINE void cfg_tx_pin(uint32_t pin_number)
{
 nrf_gpio_cfg(
 pin_number,
 NRF_GPIO_PIN_DIR_OUTPUT,
 NRF_GPIO_PIN_INPUT_CONNECT, // Connect for single pix tx/rx
 NRF_GPIO_PIN_PULLUP, // If not using external pull-up
 NRF_GPIO_PIN_H0D1, // Open drain
 NRF_GPIO_PIN_NOSENSE);
} 
 Then change this around line 1424 in uart_nrfx_uarte.c : 
 nrf_gpio_pin_write(config->pseltxd, 1);
	nrf_gpio_cfg_output(config->pseltxd); 
 to this: 
 nrf_gpio_pin_write(config->pseltxd, 1);
	cfg_tx_pin(config->pseltxd);

Use UART, but make the TX pin open drain.

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