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boards: reel_board: enable pull-up on UART RX pin 

Enable pull-up on UART RX pin to reduce power consumption.
If the board is powered by battery and the debugger is
not connected via USB to the host, the SoC consumes up
to 2mA more than expected.
The consumption increases because RX pin is floating
(High-Impedance state of pin B from Dual-Supply Bus Transceiver).

Signed-off-by: Johann Fischer <j.fischer@phytec.de>
This commit is contained in:
Johann Fischer 2019-02-18 16:39:14 +01:00 committed by Anas Nashif
parent f9e73c90f2
commit b5b728495b
1 changed files with 14 additions and 0 deletions
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14
boards/arm/reel_board/board.c
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@ -24,6 +24,20 @@ static int board_reel_board_init(struct device *dev)
gpio->OUTSET = BIT(PERIPH_PON_PIN);
/*
* Enable pull-up on UART RX pin to reduce power consumption.
* If the board is powered by battery and the debugger is
* not connected via USB to the host, the SoC consumes up
* to 2mA more than expected.
* The consumption increases because RX pin is floating
* (High-Impedance state of pin B from Dual-Supply Bus Transceiver).
*/
gpio = NRF_P0;
gpio->PIN_CNF[DT_NORDIC_NRF_UART_0_RX_PIN] =
(GPIO_PIN_CNF_INPUT_Disconnect << GPIO_PIN_CNF_INPUT_Pos) |
(GPIO_PIN_CNF_PULL_Pullup << GPIO_PIN_CNF_PULL_Pos) |
(GPIO_PIN_CNF_DIR_Input << GPIO_PIN_CNF_DIR_Pos);
return 0;
}