clean up on docs

README.md

@@ -1,8 +1,8 @@
 # AVR I2C Driver Example
 
-This project is to have a simple example of a primary I2C communication on an ATtiny85 with documentation.
+This project is to have a simple example of a controller I2C communication on an ATtiny85 with documentation.
 
-Supports writing and reading from secondary devices.
+Supports writing and reading from target devices.
 
 ## Project Structure
 
@@ -16,11 +16,11 @@ Supports writing and reading from secondary devices.
 ## Demo
 
 The demo has an ATtiny85 loaded with the code in this project hooked up to an arduino uno using the Wire library to
-act as a secondary device to talk to.
+act as a target device to talk to.
 
 Actions performed:
-- The primary (ATtiny85) sends "Hello, World!" to the secondary (Arduino Uno) device.
-- The primary requests a read from the secondary to toggle the LED.
+- The controller (ATtiny85) sends "Hello, World!" to the target (Arduino Uno) device.
+- The controller requests a read from the target to toggle the LED.
 
 https://github.com/user-attachments/assets/6c168a57-7b3c-4304-adfc-d2d9f486735c
 

src/driver/i2c.c

@@ -2,6 +2,7 @@
 #include <util/delay.h>
 
 // data sheet says between 50 and 300 nanoseconds
+// this is 0.2 microseconds which is 200 nanoseconds
 #define WAIT 0.2
 
 #define STATUS_CLOCK_8_BITS (_BV(USISIF)|_BV(USIOIF)|_BV(USIPF)|_BV(USIDC) | \
@@ -156,23 +157,23 @@ unsigned char i2c_write_byte(unsigned char data) {
 /**
  * Read the next byte.
  *
- * @param[in] nack True for reading more, false otherwise.
+ * @param[in] ack True for reading more, false otherwise.
  * @return The read byte.
  */
-unsigned char i2c_read_byte(bool nack) {
+unsigned char i2c_read_byte(bool ack) {
   // change data pin to input
   i2c_bus &= ~_BV(i2c_sda);
   unsigned char data = transfer(STATUS_CLOCK_8_BITS);
   // change back to output
   i2c_bus |= _BV(i2c_sda);
-  if (nack) {
-    // HIGH means read another byte
+  if (ack) {
+    // LOW means read another byte
     i2c_data = 0x00;
   } else {
-    // LOW means stop sending
+    // HIGH means stop sending
     i2c_data = 0xff;
   }
-  // send nack
+  // send n/ack
   transfer(STATUS_CLOCK_1_BIT);
   return data;
 }

src/main.c

@@ -41,7 +41,8 @@ int main (void) {
     i2c_stop();
     _delay_ms(1000);
 
-    if(!i2c_start()) break;
+    if(!i2c_start()) error_loop();
+
     i2c_write_address(TARGET_ADDR, false);
 
     unsigned char byte = i2c_read_byte(false);