From e036c19d063c543090d01ea841ac343a48276f6d Mon Sep 17 00:00:00 2001 From: Ryan Date: Mon, 7 Feb 2022 04:02:45 +1100 Subject: Add SN74x138 demultiplexer driver (#16217) --- drivers/gpio/sn74x138.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++++ drivers/gpio/sn74x138.h | 48 ++++++++++++++++++++++++++++++++++++ 2 files changed, 113 insertions(+) create mode 100644 drivers/gpio/sn74x138.c create mode 100644 drivers/gpio/sn74x138.h (limited to 'drivers') diff --git a/drivers/gpio/sn74x138.c b/drivers/gpio/sn74x138.c new file mode 100644 index 0000000000..222e5db56c --- /dev/null +++ b/drivers/gpio/sn74x138.c @@ -0,0 +1,65 @@ +/* Copyright 2022 + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see . + */ + +#include "sn74x138.h" +#include "gpio.h" + +#define ADDRESS_PIN_COUNT 3 + +#ifndef SN74X138_ADDRESS_PINS +# error sn74x138: no address pins defined! +#endif + +static const pin_t address_pins[ADDRESS_PIN_COUNT] = SN74X138_ADDRESS_PINS; + +void sn74x138_init(void) { + for (int i = 0; i < ADDRESS_PIN_COUNT; i++) { + setPinOutput(address_pins[i]); + writePinLow(address_pins[i]); + } + +#if defined(SN74X138_E1_PIN) + setPinOutput(SN74X138_E1_PIN); + writePinHigh(SN74X138_E1_PIN); +#endif + +#if defined(SN74X138_E2_PIN) + setPinOutput(SN74X138_E2_PIN); + writePinHigh(SN74X138_E2_PIN); +#endif +#if defined(SN74X138_E3_PIN) + setPinOutput(SN74X138_E3_PIN); + writePinLow(SN74X138_E3_PIN); +#endif +} + +void sn74x138_set_enabled(bool enabled) { +#if defined(SN74X138_E1_PIN) + writePin(SN74X138_E1_PIN, !enabled); +#endif +#if defined(SN74X138_E2_PIN) + writePin(SN74X138_E2_PIN, !enabled); +#endif +#if defined(SN74X138_E3_PIN) + writePin(SN74X138_E3_PIN, enabled); +#endif +} + +void sn74x138_set_addr(uint8_t address) { + for (int i = 0; i < ADDRESS_PIN_COUNT; i++) { + writePin(address_pins[i], address & (1 << i)); + } +} diff --git a/drivers/gpio/sn74x138.h b/drivers/gpio/sn74x138.h new file mode 100644 index 0000000000..d4d0b6574d --- /dev/null +++ b/drivers/gpio/sn74x138.h @@ -0,0 +1,48 @@ +/* Copyright 2022 + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see . + */ + +#pragma once + +#include +#include + +/** + * Driver for 74x138 3-to-8 decoder/demultiplexer with inverting outputs + * https://assets.nexperia.com/documents/data-sheet/74HC_HCT138.pdf + */ + +/** + * Initialize the address and output enable pins. + */ +void sn74x138_init(void); + +/** + * Set the enabled state. + * + * When enabled is true, pulls the E1 and E2 pins low, and the E3 pin high. + * + * \param enabled The enable state to set. + */ +void sn74x138_set_enabled(bool enabled); + +/** + * Set the output pin address. + * + * The selected output pin will be pulled low, while the remaining output pins will be high. + * + * \param address The address to set, from 0 to 7. + */ +void sn74x138_set_addr(uint8_t address); -- cgit v1.2.3