189 lines
4.5 KiB
C
189 lines
4.5 KiB
C
/*
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* mcp23s08.c:
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* Extend wiringPi with the MCP 23s08 SPI GPIO expander chip
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* Copyright (c) 2013 Gordon Henderson
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***********************************************************************
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* This file is part of wiringPi:
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* https://projects.drogon.net/raspberry-pi/wiringpi/
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*
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* wiringPi is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
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*
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* wiringPi 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 Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with wiringPi.
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* If not, see <http://www.gnu.org/licenses/>.
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***********************************************************************
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*/
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#include <stdio.h>
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#include <stdint.h>
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#include "wiringPi.h"
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#include "wiringPiSPI.h"
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#include "mcp23x0817.h"
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#include "mcp23s08.h"
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#define MCP_SPEED 4000000
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/*
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* writeByte:
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* Write a byte to a register on the MCP23s08 on the SPI bus.
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*********************************************************************************
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*/
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static void writeByte (uint8_t spiPort, uint8_t devId, uint8_t reg, uint8_t data)
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{
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uint8_t spiData [4] ;
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spiData [0] = CMD_WRITE | ((devId & 7) << 1) ;
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spiData [1] = reg ;
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spiData [2] = data ;
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wiringPiSPIDataRW (spiPort, spiData, 3) ;
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}
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/*
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* readByte:
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* Read a byte from a register on the MCP23s08 on the SPI bus.
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*********************************************************************************
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*/
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static uint8_t readByte (uint8_t spiPort, uint8_t devId, uint8_t reg)
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{
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uint8_t spiData [4] ;
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spiData [0] = CMD_READ | ((devId & 7) << 1) ;
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spiData [1] = reg ;
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wiringPiSPIDataRW (spiPort, spiData, 3) ;
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return spiData [2] ;
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}
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/*
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* myPinMode:
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*********************************************************************************
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*/
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static void myPinMode (struct wiringPiNodeStruct *node, int pin, int mode)
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{
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int mask, old, reg ;
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reg = MCP23x08_IODIR ;
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mask = 1 << (pin - node->pinBase) ;
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old = readByte (node->data0, node->data1, reg) ;
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if (mode == OUTPUT)
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old &= (~mask) ;
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else
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old |= mask ;
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writeByte (node->data0, node->data1, reg, old) ;
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}
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/*
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* myPullUpDnControl:
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*********************************************************************************
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*/
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static void myPullUpDnControl (struct wiringPiNodeStruct *node, int pin, int mode)
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{
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int mask, old, reg ;
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reg = MCP23x08_GPPU ;
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mask = 1 << (pin - node->pinBase) ;
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old = readByte (node->data0, node->data1, reg) ;
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if (mode == PUD_UP)
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old |= mask ;
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else
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old &= (~mask) ;
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writeByte (node->data0, node->data1, reg, old) ;
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}
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/*
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* myDigitalWrite:
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*********************************************************************************
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*/
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static void myDigitalWrite (struct wiringPiNodeStruct *node, int pin, int value)
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{
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int bit, old ;
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bit = 1 << ((pin - node->pinBase) & 7) ;
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old = node->data2 ;
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if (value == LOW)
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old &= (~bit) ;
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else
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old |= bit ;
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writeByte (node->data0, node->data1, MCP23x08_GPIO, old) ;
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node->data2 = old ;
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}
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/*
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* myDigitalRead:
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*********************************************************************************
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*/
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static int myDigitalRead (struct wiringPiNodeStruct *node, int pin)
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{
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int mask, value ;
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mask = 1 << ((pin - node->pinBase) & 7) ;
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value = readByte (node->data0, node->data1, MCP23x08_GPIO) ;
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if ((value & mask) == 0)
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return LOW ;
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else
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return HIGH ;
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}
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/*
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* mcp23s08Setup:
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* Create a new instance of an MCP23s08 SPI GPIO interface. We know it
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* has 8 pins, so all we need to know here is the SPI address and the
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* user-defined pin base.
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*********************************************************************************
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*/
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int mcp23s08Setup (const int pinBase, const int spiPort, const int devId)
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{
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struct wiringPiNodeStruct *node ;
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if (wiringPiSPISetup (spiPort, MCP_SPEED) < 0)
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return FALSE ;
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writeByte (spiPort, devId, MCP23x08_IOCON, IOCON_INIT) ;
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node = wiringPiNewNode (pinBase, 8) ;
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node->data0 = spiPort ;
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node->data1 = devId ;
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node->pinMode = myPinMode ;
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node->pullUpDnControl = myPullUpDnControl ;
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node->digitalRead = myDigitalRead ;
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node->digitalWrite = myDigitalWrite ;
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node->data2 = readByte (spiPort, devId, MCP23x08_OLAT) ;
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return TRUE ;
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}
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