fix formatting, comments

HamShield.cpp

@@ -119,28 +119,24 @@ volatile long bouncer = 0;
  * @see A1846S_DEFAULT_ADDRESS
  */
 HamShield::HamShield() {
-    devAddr = A1; // devAddr is the chip select pin used by the HamShield
+    devAddr = A1846S_DEV_ADDR_SENLOW;
     sHamShield = this;
 	
     pinMode(A1, OUTPUT);
-    digitalWrite(A1, HIGH);
-    pinMode(A4, OUTPUT);
-    pinMode(A5, OUTPUT);
+    digitalWrite(A1, LOW);
 }
 
 /** Specific address constructor.
- * @param chip select pin for HamShield
+ * @param address the I2C address of the HamShield
  * @see A1846S_DEFAULT_ADDRESS
  * @see A1846S_ADDRESS_AD0_LOW
  * @see A1846S_ADDRESS_AD0_HIGH
  */
-HamShield::HamShield(uint8_t cs_pin) {
-    devAddr = cs_pin;
+HamShield::HamShield(uint8_t address) {
+    devAddr = address;
 
     pinMode(A1, OUTPUT);
-    digitalWrite(A1, HIGH);
-    pinMode(A4, OUTPUT);
-    pinMode(A5, OUTPUT);
+    digitalWrite(A1, LOW);
 }
 
 /** Power on and prepare for general usage.

HamShield.h

@@ -8,8 +8,6 @@
 #ifndef _HAMSHIELD_H_
 #define _HAMSHIELD_H_
 
-//#include "I2Cdev_rda.h"
-//#include "I2Cdev.h"
 #include "HamShield_comms.h"
 #include "SimpleFIFO.h"
 #include "AFSK.h"
@@ -263,7 +261,7 @@ class HamShield {
         static HamShield *sHamShield; // HamShield singleton, used for ISRs mostly
 		
         HamShield();
-        HamShield(uint8_t cs_pin);
+        HamShield(uint8_t address);
 
         void initialize();
         bool testConnection();

HamShield_comms.cpp

@@ -1,5 +1,5 @@
 /*
- * Based loosely on I2Cdev by Jeff Rowberg, except for all kludgy bit-banging
+ * Based loosely on I2Cdev by Jeff Rowberg
  */
 
 #include "HamShield_comms.h"
@@ -27,61 +27,35 @@ int8_t HSreadBitsW(uint8_t devAddr, uint8_t regAddr, uint8_t bitStart, uint8_t l
 
 int8_t HSreadWord(uint8_t devAddr, uint8_t regAddr, uint16_t *data)
 {
-	//return I2Cdev::readWord(devAddr, regAddr, data);
 
-	uint8_t temp;
-	uint16_t temp_dat;
-	// bitbang for great justice!
-	*data = 0;
-	cli();
-	DDRC |= ((1<<5) | (1<<4)); // set direction to output
-	sei();
-	regAddr = regAddr | (1 << 7);
+    int8_t count = 0;
+    uint32_t t1 = millis();
+	uint8_t timeout = 1000;
 
-	//cli();
-	digitalWrite(devAddr, 0); //PORTC &= ~(1<<1); //devAddr used as chip select
-	//sei();
-	for (int i = 0; i < 8; i++) {
-		temp = ((regAddr & (0x80 >> i)) != 0);
-		cli();
-		PORTC &= ~(1<<5); //digitalWrite(CLK, 0);
-		sei();
-		//digitalWrite(DAT, regAddr & (0x80 >> i));
-		temp = (PORTC & ~(1<<4)) + (temp << 4);
-		cli();
-		PORTC = temp;
-		sei();
-		delayMicroseconds(9);
-		cli();
-		PORTC |= (1<<5); //digitalWrite(CLK, 1);
-		sei();
-		delayMicroseconds(9);
+	Wire.beginTransmission(devAddr);
+    Wire.write(regAddr);
+    Wire.endTransmission(false);
+    Wire.requestFrom((int)devAddr, 2); // length=words, this wants bytes
+        
+    bool msb = true; // starts with MSB, then LSB
+    for (; Wire.available() && count < 1 && (timeout == 0 || millis() - t1 < timeout);) {
+        if (msb) {
+            // first byte is bits 15-8 (MSb=15)
+            data[0] = Wire.read() << 8;
+        } else {
+            // second byte is bits 7-0 (LSb=0)
+            data[0] |= Wire.read();
+            count++;
         }
-	// change direction of DAT
-	cli();
-	DDRC &= ~(1<<4); //pinMode(DAT, INPUT);
-	sei();
-	for (int i = 15; i >= 0; i--) {
-		cli();
-		PORTC &= ~(1<<5); //digitalWrite(CLK, 0);
-		sei();
-		delayMicroseconds(9);
-		cli();
-		PORTC |= (1<<5); //digitalWrite(CLK, 1);
-		sei();
-		cli();
-		temp_dat = ((PINC & (1<<4)) != 0);
-		sei();
-		temp_dat = temp_dat << i;
-		*data |= temp_dat; // digitalRead(DAT);
-		delayMicroseconds(9);
+        msb = !msb;
     }
-	digitalWrite(devAddr, 1); //PORTC |= (1<<1);// CS
         
-	cli();	
-	DDRC &= ~((1<<5) | (1<<4)); // set direction all input (for ADC)
-	sei();
-	return 1;
+    Wire.endTransmission();
+
+    if (timeout > 0 && millis() - t1 >= timeout && count < 1) count = -1; // timeout
+    
+    return count;
+
 }
 
 
@@ -95,7 +69,7 @@ bool HSwriteBitW(uint8_t devAddr, uint8_t regAddr, uint8_t bitNum, uint16_t data
 
 bool HSwriteBitsW(uint8_t devAddr, uint8_t regAddr, uint8_t bitStart, uint8_t length, uint16_t data)
 {
-uint16_t w;
+	uint16_t w;
     if (HSreadWord(devAddr, regAddr, &w) != 0) {
         uint16_t mask = ((1 << length) - 1) << (bitStart - length + 1);
         data <<= (bitStart - length + 1); // shift data into correct position
@@ -110,60 +84,14 @@ uint16_t w;
 
 bool HSwriteWord(uint8_t devAddr, uint8_t regAddr, uint16_t data)
 {
-	//return I2Cdev::writeWord(devAddr, regAddr, data);
+    uint8_t status = 0;
 
-	uint8_t temp_reg;
-	uint16_t temp_dat;
+	Wire.beginTransmission(devAddr);
+    Wire.write(regAddr); // send address
 
-	//digitalWrite(13, HIGH);
+    Wire.write((uint8_t)(data >> 8));    // send MSB
+    Wire.write((uint8_t)data);         // send LSB
   
-	// bitbang for great justice!
-	cli();
-	DDRC |= ((1<<5) | (1<<4)); // set direction all output
-	//PORTC |= (1<<5) & (1<<4);
-	sei();
-	regAddr = regAddr & ~(1 << 7);
-	
-	//cli();
-	digitalWrite(devAddr, 0); // PORTC &= ~(1<<1); //CS
-	//sei();
-	for (int i = 0; i < 8; i++) {
-		temp_reg = ((regAddr & (0x80 >> i)) != 0);
-		cli();
-		PORTC &= ~(1<<5); //digitalWrite(CLK, 0);
-		sei();
-		//digitalWrite(DAT, regAddr & (0x80 >> i));
-		temp_reg = (PORTC & ~(1<<4)) + (temp_reg << 4);
-		cli();
-		PORTC = temp_reg;
-		sei();
-		delayMicroseconds(8);
-		cli();
-		PORTC |= (1<<5); //digitalWrite(CLK, 1);
-		sei();
-		delayMicroseconds(10);
-	}
-	for (int i = 0; i < 16; i++) {
-		temp_dat = ((data & (0x8000 >> i)) != 0);
-		cli();
-		PORTC &= ~(1<<5); //digitalWrite(CLK, 0);
-		sei();
-		//digitalWrite(DAT, data & (0x80000 >> i));
-		temp_reg = (PORTC & ~(1<<4)) + (temp_dat << 4);
-		cli();
-		PORTC = temp_reg;
-		sei();
-		delayMicroseconds(7);
-		cli();
-		PORTC |= (1<<5); //digitalWrite(CLK, 1);
-		sei();
-		delayMicroseconds(10);
-	}
-	
-	digitalWrite(devAddr, 1); //PORTC |= (1<<1); //CS
-	
-	cli();
-	DDRC &= ~((1<<5) | (1<<4)); // set direction to input for ADC
-	sei();
-	return true;
+    status = Wire.endTransmission();
+    return status == 0;
 }

HamShield_comms.h

@@ -5,11 +5,7 @@
 #define _HAMSHIELD_COMMS_H_
 
 #include "Arduino.h"
-//#include "I2Cdev.h"
-
-#define nSEN A1
-#define CLK A5
-#define DAT A4
+#include "Wire.h"
 
 int8_t HSreadBitW(uint8_t devAddr, uint8_t regAddr, uint8_t bitNum, uint16_t *data);
 int8_t HSreadBitsW(uint8_t devAddr, uint8_t regAddr, uint8_t bitStart, uint8_t length, uint16_t *data);

README.md

@@ -1,6 +1,26 @@
 # HamShield
 
-The master branch is intended for use with HamShield hardware -09 and above.
+Please note that I2C communications are not officially supported.
+
+The RF transciever on the HamShield has trouble driving large I2C bus capacitances (over 40pF). What this means is that it works well if the transciever is on the same physical PCB as the microcontroller (assuming good layout), but works poorly as a daughterboard.
+
+We recommend that you use the master branch, which uses a custom communications protocol. That custom protocol does not have the same bus capacitance limitation. You're welcome to play around with I2C if you want, but it may cause instability issues.
+
+## Hardware Changes Necessary
+
+The i2c-comms branch is not intended for use with a stock HamShield.
+
+To use i2c communications with a HamShield 09 or above, you must first make several hardware changes to the board.
+
+1. Remove R2
+2. Short the pads of R17 (either with a wire or a low value resistor).
+
+Then make sure that you pull the nCS pin correctly. Changing nCS changes the I2C address of the HamShield:
+
+- nCS is logic high: A1846S_DEV_ADDR_SENHIGH 0b0101110
+- nCS is logic low: A1846S_DEV_ADDR_SENLOW  0b1110001
+
+
 
 HamShield Arduino Library and Example Sketches