wiringPi_Blueberry/devLib/gertboard.c
2023-08-11 15:53:17 +08:00

165 lines
4.0 KiB
C

/*
* gertboard.c:
* Access routines for the SPI devices on the Gertboard
* Copyright (c) 2012 Gordon Henderson
*
* The Gertboard has:
*
* An MCP3002 dual-channel A to D convertor connected
* to the SPI bus, selected by chip-select A, and:
*
* An MCP4802 dual-channel D to A convertor connected
* to the SPI bus, selected via chip-select B.
*
***********************************************************************
* This file is part of wiringPi:
* https://projects.drogon.net/raspberry-pi/wiringpi/
*
* wiringPi is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* wiringPi 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with wiringPi.
* If not, see <http://www.gnu.org/licenses/>.
***********************************************************************
*/
#include <stdio.h>
#include <stdint.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/spi/spidev.h>
#include <wiringPi.h>
#include <wiringPiSPI.h>
#include "gertboard.h"
// The A-D convertor won't run at more than 1MHz @ 3.3v
#define SPI_ADC_SPEED 1000000
#define SPI_DAC_SPEED 1000000
#define SPI_A2D 0
#define SPI_D2A 1
/*
* gertboardAnalogWrite:
* Write an 8-bit data value to the MCP4802 Analog to digital
* convertor on the Gertboard.
*********************************************************************************
*/
void gertboardAnalogWrite (const int chan, const int value)
{
uint8_t spiData [2] ;
uint8_t chanBits, dataBits ;
if (chan == 0)
chanBits = 0x30 ;
else
chanBits = 0xB0 ;
chanBits |= ((value >> 4) & 0x0F) ;
dataBits = ((value << 4) & 0xF0) ;
spiData [0] = chanBits ;
spiData [1] = dataBits ;
wiringPiSPIDataRW (SPI_D2A, spiData, 2) ;
}
/*
* gertboardAnalogRead:
* Return the analog value of the given channel (0/1).
* The A/D is a 10-bit device
*********************************************************************************
*/
int gertboardAnalogRead (const int chan)
{
uint8_t spiData [2] ;
uint8_t chanBits ;
if (chan == 0)
chanBits = 0b11010000 ;
else
chanBits = 0b11110000 ;
spiData [0] = chanBits ;
spiData [1] = 0 ;
wiringPiSPIDataRW (SPI_A2D, spiData, 2) ;
return ((spiData [0] << 8) | (spiData [1] >> 1)) & 0x3FF ;
}
/*
* gertboardSPISetup:
* Initialise the SPI bus, etc.
*********************************************************************************
*/
int gertboardSPISetup (void)
{
if (wiringPiSPISetup (SPI_A2D, SPI_ADC_SPEED) < 0)
return -1 ;
if (wiringPiSPISetup (SPI_D2A, SPI_DAC_SPEED) < 0)
return -1 ;
return 0 ;
}
/*
* New wiringPi node extension methods.
*********************************************************************************
*/
static int myAnalogRead (struct wiringPiNodeStruct *node, const int chan)
{
return gertboardAnalogRead (chan - node->pinBase) ;
}
static void myAnalogWrite (struct wiringPiNodeStruct *node, const int chan, const int value)
{
gertboardAnalogWrite (chan - node->pinBase, value) ;
}
/*
* gertboardAnalogSetup:
* Create a new wiringPi device node for the analog devices on the
* Gertboard. We create one node with 2 pins - each pin being read
* and write - although the operations actually go to different
* hardware devices.
*********************************************************************************
*/
int gertboardAnalogSetup (const int pinBase)
{
struct wiringPiNodeStruct *node ;
int x ;
if (( x = gertboardSPISetup ()) != 0)
return x;
node = wiringPiNewNode (pinBase, 2) ;
node->analogRead = myAnalogRead ;
node->analogWrite = myAnalogWrite ;
return 0 ;
}