Diff: swspi.cpp

Revision:

0:8a4db0f083fc

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/swspi.cpp	Sun Jun 11 04:04:19 2017 +0000
@@ -0,0 +1,125 @@
+// Software (bit-banged) SPI Module supporting two modes.
+// Each mode consists of a CS and CPHA mode 
+//
+
+#include <swspi.h>
+#include "mbed.h"
+
+
+swspi::swspi(PinName mosiPin, PinName misoPin, PinName sckPin, PinName ss1Pin, PinName ss2Pin)
+{
+    mosiP = new DigitalOut(mosiPin);
+    misoP = new DigitalIn(misoPin);
+    sckP = new DigitalOut(sckPin);
+    ss1P = new DigitalOut(ss1Pin);
+    ss2P = new DigitalOut(ss2Pin);
+}
+
+void swspi::init()
+{
+    sckP->write(0);
+    mosiP->write(0);
+    ss1P->write(1);
+    ss2P->write(1);
+}
+
+uint8_t swspi::spiRead(uint8_t reg, int cpha, int ss)
+{
+    uint8_t val;
+    
+    _spi_mutex.lock();
+    _cpha = cpha;
+    _ss = ss;
+    _setSlaveSelect(0);
+    _transfer(reg & ~SPI_WRITE_MASK); // Send the address with the write mask off
+    val = _transfer(0); // The written value is ignored, reg value is read
+    _setSlaveSelect(1);
+    _spi_mutex.unlock();
+    
+    return val;
+}
+
+uint8_t swspi::spiWrite(uint8_t reg, uint8_t val, int cpha, int ss)
+{
+    uint8_t status = 0;
+    
+    _spi_mutex.lock();
+    _cpha = cpha;
+    _ss = ss;
+    _setSlaveSelect(0);
+    status = _transfer(reg | SPI_WRITE_MASK); // Send the address with the write mask on
+    _transfer(val); // New value follows
+    _setSlaveSelect(1);
+    _spi_mutex.unlock();
+    
+    return status;
+}
+
+uint8_t swspi::spiBurstRead(uint8_t reg, uint8_t* dest, uint8_t len, int cpha, int ss)
+{
+    uint8_t status = 0;
+    
+    _spi_mutex.lock();
+    _cpha = cpha;
+    _ss = ss;
+    _setSlaveSelect(0);
+    status = _transfer(reg & ~SPI_WRITE_MASK); // Send the start address with the write mask off
+    while (len--)
+        *dest++ = _transfer(0);
+    _setSlaveSelect(1);
+    _spi_mutex.unlock();
+    
+    return status;
+}
+
+uint8_t swspi::spiBurstWrite(uint8_t reg, const uint8_t* src, uint8_t len, int cpha, int ss)
+{
+    uint8_t status = 0;
+    
+    _spi_mutex.lock();
+    _cpha = cpha;
+    _ss = ss;
+    _setSlaveSelect(0);
+    status = _transfer(reg | SPI_WRITE_MASK); // Send the start address with the write mask on
+    while (len--)
+        _transfer(*src++);
+    _setSlaveSelect(1);
+    _spi_mutex.unlock();
+    
+    return status;
+}
+
+void swspi::_setSlaveSelect(int v)
+{
+    if (_ss == 1)
+      ss1P->write(v);
+    else
+      ss2P->write(v);
+}
+
+uint8_t swspi::_transfer(uint8_t v)
+{
+    uint8_t reply = 0;
+
+    if (_cpha == 0) {
+        // Sample on rising clock edge
+        for (int i=7; i>=0; i--) {
+            reply <<= 1;
+            mosiP->write( (v & (1<<i)) != 0 ? 1 : 0 );
+            sckP->write(1);
+            if (misoP->read() == 1) reply |= 1;
+            sckP->write(0);
+        }
+    } else {
+        // Sample on falling clock edge
+        for (int i=7; i>=0; i--) {
+            reply <<= 1;
+            sckP->write(1);
+            mosiP->write( (v & (1<<i)) != 0 ? 1 : 0 );
+            sckP->write(0);
+            if (misoP->read() == 1) reply |= 1;
+        }
+    }
+
+    return reply;
+}