From 9d678fbace2e4931e39ab5b95b2ec7493a18f549 Mon Sep 17 00:00:00 2001
From: Blaise Thompson <blaise@untzag.com>
Date: Mon, 25 Jan 2021 12:15:05 -0600
Subject: digital-driver readme

---
 digital-driver/firmware/TinyWireS/TinyWireS.cpp | 91 +++++++++++++++++++++++++
 1 file changed, 91 insertions(+)
 create mode 100644 digital-driver/firmware/TinyWireS/TinyWireS.cpp

(limited to 'digital-driver/firmware/TinyWireS/TinyWireS.cpp')

diff --git a/digital-driver/firmware/TinyWireS/TinyWireS.cpp b/digital-driver/firmware/TinyWireS/TinyWireS.cpp
new file mode 100644
index 0000000..783e8e7
--- /dev/null
+++ b/digital-driver/firmware/TinyWireS/TinyWireS.cpp
@@ -0,0 +1,91 @@
+/*
+  TinyWireS.cpp - a wrapper class for Don Blake's usiTwiSlave routines.
+  Provides TWI/I2C Slave functionality on ATtiny processers in Arduino environment.
+  1/23/2011 BroHogan -  brohoganx10 at gmail dot com
+
+  **** See TinyWireS.h for Credits and Usage information ****
+
+  This library is free software; you can redistribute it and/or modify it under the
+  terms of the GNU General Public License as published by the Free Software
+  Foundation; either version 2.1 of the License, or any later version.
+  This program 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 General Public License for more details.
+*/
+
+extern "C" {
+  #include <inttypes.h>
+  #include "usiTwiSlave.h"
+  #include <avr/interrupt.h>
+  }
+
+#include "TinyWireS.h"
+#include "Arduino.h"
+
+// Constructors ////////////////////////////////////////////////////////////////
+
+USI_TWI_S::USI_TWI_S(){
+}
+
+
+// Public Methods //////////////////////////////////////////////////////////////
+
+void USI_TWI_S::begin(uint8_t slaveAddr){ // initialize I2C lib
+  usiTwiSlaveInit(slaveAddr); 
+}
+
+void USI_TWI_S::send(uint8_t data){  // send it back to master
+  usiTwiTransmitByte(data);
+}
+
+uint8_t USI_TWI_S::available(){ // the bytes available that haven't been read yet
+  return usiTwiAmountDataInReceiveBuffer(); 
+  //return usiTwiDataInReceiveBuffer(); // This is wrong as far as the Wire API is concerned since it returns boolean and not amount
+}
+ 
+uint8_t USI_TWI_S::receive(){ // returns the bytes received one at a time
+  return usiTwiReceiveByte(); 
+}
+
+// sets function called on slave write
+void USI_TWI_S::onReceive( void (*function)(uint8_t) )
+{
+  usi_onReceiverPtr = function;
+}
+
+// sets function called on slave read
+void USI_TWI_S::onRequest( void (*function)(void) )
+{
+  usi_onRequestPtr = function;
+}
+
+// This routine is no longer used now that the usiTwiSlave is completely
+// interrupt driven. The function is maintained here so that programs
+// written for the pre-interrupt driven version will still compile and function.
+void TinyWireS_stop_check()
+{
+  // empty functions
+}
+
+// Implement a delay loop that checks for the stop bit (basically direct copy of the stock arduino implementation from wiring.c)
+// I don't think this function is necessary now that the 
+// usiTwiSlave is completely interrupt driven. I'm not sure, and the function is 
+// behaviorally harmless because TinyWireS_stop_check() is empty, so I'm leaving it alone.
+void tws_delay(unsigned long ms)
+{
+    uint16_t start = (uint16_t)micros();
+    while (ms > 0)
+    {
+        TinyWireS_stop_check();
+        if (((uint16_t)micros() - start) >= 1000)
+        {
+            ms--;
+            start += 1000;
+        }
+    }
+}
+
+// Preinstantiate Objects //////////////////////////////////////////////////////
+
+USI_TWI_S TinyWireS = USI_TWI_S();
+
-- 
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