From bfbbda4f9e534348f1df6f06f151c2b20b60327a Mon Sep 17 00:00:00 2001
From: pichenettes <ol.gillet@gmail.com>
Date: Mon, 2 May 2011 02:38:56 +0200
Subject: [PATCH] Added support for SPI on UART0

---
 devices/mcp492x.h | 13 +++----
 gpio.h            |  4 +++
 spi.h             | 92 ++++++++++++++++++++++++++++++++++++++++++++---
 3 files changed, 96 insertions(+), 13 deletions(-)

diff --git a/devices/mcp492x.h b/devices/mcp492x.h
index 44fcc68..1b16ee1 100755
--- a/devices/mcp492x.h
+++ b/devices/mcp492x.h
@@ -34,7 +34,7 @@ enum DacVoltageReference {
   UNBUFFERED_REFERENCE
 };
 
-template<typename slave_select,
+template<typename Interface,
          DacVoltageReference voltage_reference = UNBUFFERED_REFERENCE,
          uint8_t gain = 1>
 class Dac {
@@ -46,14 +46,14 @@ class Dac {
   Dac() { }
 
   static void Init() {
-    DacInterface::Init();
+    Interface::Init();
   }
 
-  static void Write(uint8_t value) {
+  static inline void Write(uint8_t value) {
     Write(value, 0);
   }
 
-  static void Write(uint8_t value, uint8_t channel) {
+  static inline void Write(uint8_t value, uint8_t channel) {
     value = Swap4(value);
     uint8_t command;
     command = (value & 0x0f) | 0x10;
@@ -66,11 +66,8 @@ class Dac {
     if (gain == 1) {
       command |= 0x20;
     }
-    DacInterface::WriteWord(command, value & 0xf0);
+    Interface::WriteWord(command, value & 0xf0);
   }
-
- private:
-  typedef SpiMaster<slave_select, MSB_FIRST, kDacSpeed> DacInterface;
 };
 
 }  // namespace avrlib
diff --git a/gpio.h b/gpio.h
index 83891dc..254f830 100755
--- a/gpio.h
+++ b/gpio.h
@@ -255,6 +255,10 @@ typedef Gpio<PortB, 4> SpiMISO;
 typedef Gpio<PortB, 3> SpiMOSI;
 typedef Gpio<PortB, 2> SpiSS;
 
+typedef Gpio<PortD, 4> UartSpiXCK;
+typedef Gpio<PortD, 1> UartSpiTX;
+typedef Gpio<PortD, 0> UartSpiRX;
+
 #endif  // ATMEGA328P
 
 // Two specializations of the numbered pin template, one which clears the timer
diff --git a/spi.h b/spi.h
index c5563da..7902279 100644
--- a/spi.h
+++ b/spi.h
@@ -87,21 +87,39 @@ class SpiMaster {
 
   static inline void Write(uint8_t v) {
     SlaveSelect::Low();
-    SPDR = v;
+    Overwrite(v);
+    Wait();
+    SlaveSelect::High();
+  }
+  
+  static inline void Wait() {
     while (!TransferComplete::value());
+  }
+  
+  static inline void OptimisticWait() {
+    Wait();
+  }
+  
+  static inline void Strobe() {
     SlaveSelect::High();
+    SlaveSelect::Low();
+  }
+  
+  static inline void Overwrite(uint8_t v) {
+    SPDR = v;
   }
 
   static inline void WriteWord(uint8_t a, uint8_t b) {
     SlaveSelect::Low();
-    SPDR = a;
-    while (!TransferComplete::value());
-    SPDR = b;
-    while (!TransferComplete::value());
+    Overwrite(a);
+    Wait();
+    Overwrite(b);
+    Wait();
     SlaveSelect::High();
   }
 };
 
+
 template<typename SlaveSelect,
          DataOrder order = MSB_FIRST,
          bool enable_interrupt = false>
@@ -136,6 +154,70 @@ class SpiSlave {
   }
 };
 
+
+template<typename SlaveSelect,
+         DataOrder order = MSB_FIRST,
+         uint8_t speed = 2>
+class UartSpiMaster {
+ public:
+  enum {
+    buffer_size = 0,
+    data_size = 8
+  };
+
+  static void Init() {
+    SlaveSelect::set_mode(DIGITAL_OUTPUT);
+    SlaveSelect::High();
+
+    UBRR0 = 0;
+
+    UartSpiXCK::set_mode(DIGITAL_OUTPUT);
+    UartSpiTX::set_mode(DIGITAL_OUTPUT);
+    UartSpiRX::set_mode(DIGITAL_INPUT);
+    
+    // Set UART to SPI Master mode.
+    UCSR0C = _BV(UMSEL01) | _BV(UMSEL00);
+    
+    // Enable TX and RX
+    UCSR0B = _BV(RXEN0) | _BV(TXEN0);
+    
+    UBRR0 = (speed / 2) - 1;
+  }
+
+  static inline void Write(uint8_t v) {
+    SlaveSelect::Low();
+    Overwrite(v);
+    Wait();
+    SlaveSelect::High();
+  }
+  
+  static inline void Wait() {
+    while (!UCSR0A & _BV(UDRE0));
+  }
+  
+  static inline void OptimisticWait() { }
+  
+  static inline void Strobe() {
+    SlaveSelect::High();
+    SlaveSelect::Low();
+  }
+  
+  static inline void Overwrite(uint8_t v) {
+    UDR0 = v;
+  }
+  
+
+  static inline void WriteWord(uint8_t a, uint8_t b) {
+    SlaveSelect::Low();
+    Overwrite(a);
+    Wait();
+    Overwrite(b);
+    Wait();
+    SlaveSelect::High();
+  }
+};
+
+
 #define SPI_RECEIVE ISR(SPI_STC_vect)
 
 }  // namespace avrlib