From 00341fa776ba37161a0ebd1962c6c311dc3a4a7e Mon Sep 17 00:00:00 2001
From: Porter Fencl <pfencl@wisc.edu>
Date: Mon, 29 Sep 2025 18:14:59 -0500
Subject: [PATCH] finished new member task 1

---
 src/main.cpp     | 11 +++++-
 src/mcp23017.cpp | 94 +++++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 100 insertions(+), 5 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index c58189e..bf59117 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -12,7 +12,7 @@
 #endif
 
 // TODO: declare mcp23017 object
-
+Mcp23017 obj1(0x20);
 void setup() {
   // initialize Serial for printouts
   Serial.begin(115200);
@@ -23,8 +23,17 @@ void setup() {
     //Make sure to check if it is an Active-High or Active-Low reset
   #endif
   // TODO: initialize I2C and mcp23017 object
+  Wire.begin();
+  uint8_t numbers[8] = {0, 0, 0, 0, 0, 1, 0, 0};
+  obj1.begin(numbers);
 }
 
 void loop() {
   // TODO: Write tests here
+  obj1.set_state(7, 1);
+  Serial.println(obj1.get_state(5));
+  delay(1000);
+  obj1.set_state(7, 0);
+  delay(1000);
+  Serial.println(obj1.get_state(5));
 }
\ No newline at end of file
diff --git a/src/mcp23017.cpp b/src/mcp23017.cpp
index 9cb2515..79a8655 100644
--- a/src/mcp23017.cpp
+++ b/src/mcp23017.cpp
@@ -5,26 +5,95 @@
 
 // TODO: Initialize i2cBus member
 Mcp23017::Mcp23017(int addr) {
-
+    this->addr = addr;
 }
 
 uint8_t Mcp23017::get_dir(int pin) {
-    return 0;
+    
+    //gets information from Mcp23017 register 0x00
+    Wire.beginTransmission(addr);
+    Wire.write(0x00);
+    Wire.endTransmission();
+
+    //requests 1 byte from register 0x00 in Mcp23017
+    Wire.requestFrom(addr, 1);
+
+    //reads from the register and shifts the bit position to the LSB, then ands with 1 to get a 1 or 0
+    return (Wire.read() >> pin) & 1; 
+
 }
 
 
 // TODO: Read from state register
 uint8_t Mcp23017::get_state(int pin) {
-    return 0;
+
+    Wire.beginTransmission(addr);
+    Wire.write(0x12);
+    Wire.endTransmission();
+
+    Wire.requestFrom(addr, 1);
+
+    //reads from the register and shifts the bit position to the LSB, then ands with 1 to get a 1 or 0
+    return (Wire.read() >> pin) & 1; 
+
+    
+
 }
 
 // TODO: Write to directions register
+// 1: input  0: output
 int Mcp23017::set_dir(int pin, uint8_t dir) {
+    // calls IODIRA for the read
+    Wire.beginTransmission(addr); //addr << 1 makes addr  bit with LSB = 0
+    Wire.write(0x00); // writes the register offset
+    Wire.endTransmission();
+    
+    //reads the byte value from the register
+    uint8_t number;
+    Wire.requestFrom(addr, 1);
+    number = Wire.read();
+
+    // changes the byte from the register that will convert the correct pin to a 1 or 0
+    if (dir == 1) {
+        number = number | (1 << pin); // number is all 0s except a 1 in the input pin position
+    } else {
+        number = number & ~(1 << pin); // number is all 1s except a 0 in the input pin position
+    }
+    
+    //writes the new register data including the changed pin back to the register
+    Wire.beginTransmission(addr); //addr << 1 makes addr  bit with LSB = 0
+    Wire.write(0x00); // writes the register offset
+    Wire.write(number); // writes the new data
+    Wire.endTransmission();
+
     return 0;
 }
 
 // TODO: Write to state register
 int Mcp23017::set_state(int pin, uint8_t val) {
+    // calls GPIO for the read
+    Wire.beginTransmission(addr); //addr << 1 makes addr  bit with LSB = 0
+    Wire.write(0x12); // writes the register offset
+    Wire.endTransmission();
+    
+    //reads the byte value from the register
+    uint8_t number;
+    Wire.requestFrom(addr, 1);
+    number = Wire.read();
+
+    // changes the byte from the register that will convert the correct pin to a 1 or 0
+    if (val == 1) {
+        number = number | (1 << pin); // number is all 0s except a 1 in the input pin position
+    } else {
+        number = number & ~(1 << pin); // number is all 1s except a 0 in the input pin position
+    }
+    
+    //writes the new register data including the changed pin back to the register
+    Wire.beginTransmission(addr); //addr << 1 makes addr  bit with LSB = 0
+    Wire.write(0x12); // writes the register offset
+    Wire.write(number); // writes the new data
+    Wire.endTransmission();
+
     return 0;
 }
 
@@ -34,6 +103,23 @@ int Mcp23017::begin(uint8_t directions[8]) {
     int rc;
 
     // TODO: Add device ID check
+    Wire.beginTransmission(addr); //addr << 1 makes addr  bit with LSB = 0
+    Wire.write(0x00); // writes the register offset
+    Wire.endTransmission();
+    
+    // sets each bit in IODIRA according to the bits in directions
+    Wire.requestFrom(addr, 1);
+    uint8_t s = Wire.read();
+    Serial.printf("%d, %d\n",s, addr);
+    if (s == 0xFF) {          // if the read is all 1s then the default value is correct
+        for (int i = 0; i < 8; i++) {
+            this->set_dir(i, directions[i]);
+        }
+        return 0;
+    } else {
+        return 1;   // returns 1 if the default value is wrong
+    }
+    
 
-    return 0;
+    
 }