179 lines
4.3 KiB
C
179 lines
4.3 KiB
C
/*
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* piFace.:
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* Arduino compatable (ish) Wiring library for the Raspberry Pi
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* Copyright (c) 2012-2013 Gordon Henderson
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*
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* This file to interface with the PiFace peripheral device which
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* has an MCP23S17 GPIO device connected via the SPI bus.
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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 "../wiringPi/mcp23x0817.h"
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#include "piFace.h"
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#define PIFACE_SPEED 4000000
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#define PIFACE_DEVNO 0
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/*
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* writeByte:
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* Write a byte to a register on the MCP23S17 on the SPI bus.
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*********************************************************************************
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*/
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static void writeByte (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 ;
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spiData [1] = reg ;
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spiData [2] = data ;
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wiringPiSPIDataRW (PIFACE_DEVNO, 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 MCP23S17 on the SPI bus.
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*********************************************************************************
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*/
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static uint8_t readByte (uint8_t reg)
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{
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uint8_t spiData [4] ;
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spiData [0] = CMD_READ ;
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spiData [1] = reg ;
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wiringPiSPIDataRW (PIFACE_DEVNO, spiData, 3) ;
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return spiData [2] ;
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}
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/*
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* myDigitalWrite:
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* Perform the digitalWrite function on the PiFace board
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*********************************************************************************
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*/
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void myDigitalWrite (struct wiringPiNodeStruct *node, int pin, int value)
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{
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uint8_t mask, old ;
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pin -= node->pinBase ;
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mask = 1 << pin ;
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old = readByte (MCP23x17_GPIOA) ;
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if (value == 0)
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old &= (~mask) ;
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else
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old |= mask ;
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writeByte (MCP23x17_GPIOA, old) ;
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}
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/*
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* myDigitalRead:
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* Perform the digitalRead function on the PiFace board
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*********************************************************************************
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*/
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int myDigitalRead (struct wiringPiNodeStruct *node, int pin)
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{
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uint8_t mask, reg ;
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mask = 1 << ((pin - node->pinBase) & 7) ;
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if (pin < 8)
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reg = MCP23x17_GPIOB ; // Input regsiter
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else
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reg = MCP23x17_OLATA ; // Output latch regsiter
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if ((readByte (reg) & mask) != 0)
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return HIGH ;
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else
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return LOW ;
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}
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/*
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* myPullUpDnControl:
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* Perform the pullUpDnControl function on the PiFace board
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*********************************************************************************
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*/
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void myPullUpDnControl (struct wiringPiNodeStruct *node, int pin, int pud)
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{
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uint8_t mask, old ;
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mask = 1 << (pin - node->pinBase) ;
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old = readByte (MCP23x17_GPPUB) ;
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if (pud == 0)
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old &= (~mask) ;
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else
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old |= mask ;
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writeByte (MCP23x17_GPPUB, old) ;
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}
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/*
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* piFaceSetup
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* Setup the SPI interface and initialise the MCP23S17 chip
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* We create one node with 16 pins - each if the first 8 pins being read
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* and write - although the operations actually go to different
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* hardware ports. The top 8 let you read the state of the output register.
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*********************************************************************************
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*/
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int piFaceSetup (const int pinBase)
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{
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int x ;
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struct wiringPiNodeStruct *node ;
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if ((x = wiringPiSPISetup (PIFACE_DEVNO, PIFACE_SPEED)) < 0)
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return x ;
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// Setup the MCP23S17
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writeByte (MCP23x17_IOCON, IOCON_INIT) ;
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writeByte (MCP23x17_IODIRA, 0x00) ; // Port A -> Outputs
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writeByte (MCP23x17_IODIRB, 0xFF) ; // Port B -> Inputs
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node = wiringPiNewNode (pinBase, 16) ;
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node->digitalRead = myDigitalRead ;
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node->digitalWrite = myDigitalWrite ;
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node->pullUpDnControl = myPullUpDnControl ;
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return 0 ;
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}
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