Add SN74x138 demultiplexer driver (#16217)
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/* Copyright 2022
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* |
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* This program is free software: you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License as published by |
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* the Free Software Foundation, either version 2 of the License, or |
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* (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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* |
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* You should have received a copy of the GNU General Public License |
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/ |
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#include "sn74x138.h" |
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#include "gpio.h" |
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#define ADDRESS_PIN_COUNT 3 |
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#ifndef SN74X138_ADDRESS_PINS |
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# error sn74x138: no address pins defined! |
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#endif |
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static const pin_t address_pins[ADDRESS_PIN_COUNT] = SN74X138_ADDRESS_PINS; |
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void sn74x138_init(void) { |
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for (int i = 0; i < ADDRESS_PIN_COUNT; i++) { |
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setPinOutput(address_pins[i]); |
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writePinLow(address_pins[i]); |
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} |
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#if defined(SN74X138_E1_PIN) |
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setPinOutput(SN74X138_E1_PIN); |
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writePinHigh(SN74X138_E1_PIN); |
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#endif |
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#if defined(SN74X138_E2_PIN) |
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setPinOutput(SN74X138_E2_PIN); |
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writePinHigh(SN74X138_E2_PIN); |
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#endif |
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#if defined(SN74X138_E3_PIN) |
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setPinOutput(SN74X138_E3_PIN); |
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writePinLow(SN74X138_E3_PIN); |
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#endif |
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} |
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void sn74x138_set_enabled(bool enabled) { |
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#if defined(SN74X138_E1_PIN) |
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writePin(SN74X138_E1_PIN, !enabled); |
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#endif |
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#if defined(SN74X138_E2_PIN) |
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writePin(SN74X138_E2_PIN, !enabled); |
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#endif |
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#if defined(SN74X138_E3_PIN) |
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writePin(SN74X138_E3_PIN, enabled); |
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#endif |
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} |
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void sn74x138_set_addr(uint8_t address) { |
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for (int i = 0; i < ADDRESS_PIN_COUNT; i++) { |
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writePin(address_pins[i], address & (1 << i)); |
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} |
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} |
@ -0,0 +1,48 @@ |
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/* Copyright 2022
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* |
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* This program is free software: you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License as published by |
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* the Free Software Foundation, either version 2 of the License, or |
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* (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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* |
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* You should have received a copy of the GNU General Public License |
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/ |
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#pragma once |
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#include <stdint.h> |
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#include <stdbool.h> |
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/**
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* Driver for 74x138 3-to-8 decoder/demultiplexer with inverting outputs |
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* https://assets.nexperia.com/documents/data-sheet/74HC_HCT138.pdf
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*/ |
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/**
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* Initialize the address and output enable pins. |
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*/ |
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void sn74x138_init(void); |
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/**
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* Set the enabled state. |
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* |
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* When enabled is true, pulls the E1 and E2 pins low, and the E3 pin high. |
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* |
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* \param enabled The enable state to set. |
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*/ |
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void sn74x138_set_enabled(bool enabled); |
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/**
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* Set the output pin address. |
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*
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* The selected output pin will be pulled low, while the remaining output pins will be high. |
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* |
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* \param address The address to set, from 0 to 7. |
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*/ |
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void sn74x138_set_addr(uint8_t address); |
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