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76 lines
2.1 KiB
76 lines
2.1 KiB
/* |
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* mcp4802.c: |
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* Extend wiringPi with the MCP4802 SPI Digital to Analog convertor |
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* Copyright (c) 2012-2013 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 <wiringPi.h> |
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#include <wiringPiSPI.h> |
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#include "mcp4802.h" |
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/* |
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* myAnalogWrite: |
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* Write analog value on the given pin |
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********************************************************************************* |
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*/ |
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static void myAnalogWrite (struct wiringPiNodeStruct *node, int pin, int value) |
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{ |
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unsigned char spiData [2] ; |
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unsigned char chanBits, dataBits ; |
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int chan = pin - node->pinBase ; |
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if (chan == 0) |
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chanBits = 0x30 ; |
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else |
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chanBits = 0xB0 ; |
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chanBits |= ((value >> 4) & 0x0F) ; |
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dataBits = ((value << 4) & 0xF0) ; |
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spiData [0] = chanBits ; |
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spiData [1] = dataBits ; |
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wiringPiSPIDataRW (node->fd, spiData, 2) ; |
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} |
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/* |
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* mcp4802Setup: |
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* Create a new wiringPi device node for an mcp4802 on the Pi's |
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* SPI interface. |
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********************************************************************************* |
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*/ |
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int mcp4802Setup (const int pinBase, int spiChannel) |
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{ |
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struct wiringPiNodeStruct *node ; |
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if (wiringPiSPISetup (spiChannel, 1000000) < 0) |
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return FALSE ; |
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node = wiringPiNewNode (pinBase, 2) ; |
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node->fd = spiChannel ; |
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node->analogWrite = myAnalogWrite ; |
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return TRUE ; |
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}
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