I2C tested, main file now contains rough sample for use with DHT20

SHAL/Include/Core/SHAL_CORE.h

@@ -11,9 +11,56 @@
 
 #include <cstdint>
 
+//Overall init function for SHAL --------------------------
+
+void SHAL_init();
+
+//---------------------------------------------------------
+
+
+
+
 //Universal structs and defines ---------------------------
 
+typedef bool (*condition_fn_t)(void);
 
+#define SHAL_WAIT_FOR_CONDITION_US(cond, timeout_us) \
+    SHAL_wait_for_condition_us([&](){ return (cond); }, (timeout_us))
+
+#define SHAL_WAIT_FOR_CONDITION_MS(cond, timeout_ms) \
+    SHAL_wait_for_condition_ms([&](){ return (cond); }, (timeout_ms))
+
+
+
+//Currently configures systick to count down in microseconds
+void systick_init();
+
+//Max of 16ms, use SHAL_delay_ms for longer delay
+void SHAL_delay_us(uint32_t us);
+
+void SHAL_delay_ms(uint32_t ms);
+
+template<typename Condition>
+bool SHAL_wait_for_condition_us(Condition cond, uint32_t timeout_us) {
+    while (timeout_us--) {
+        if (cond()) {
+            return true; // success
+        }
+        SHAL_delay_us(1);
+    }
+    return false; // timeout
+}
+
+template<typename Condition>
+bool SHAL_wait_for_condition_ms(Condition cond, uint32_t timeout_ms) {
+    while (timeout_ms--) {
+        if (cond()) {
+            return true; // success
+        }
+        SHAL_delay_ms(1);
+    }
+    return false; // timeout
+}
 
 //---------------------------------------------------------
 

SHAL/Include/Peripheral/I2C/SHAL_I2C.h

@@ -5,6 +5,8 @@
 #ifndef SHMINGO_HAL_SHAL_I2C_H
 #define SHMINGO_HAL_SHAL_I2C_H
 
+#include <cstdio>
+
 #include "SHAL_CORE.h"
 #include "SHAL_I2C_REG.h"
 
@@ -17,16 +19,28 @@ public:
 
     void init(I2C_Pair pair) volatile;
 
-    ///
+    /// General I2C function to send commands to a device, then read back any returned data if necessary
-    /// \param addr I2C address of slave device
+    /// \param addr address of slave device
-    /// \param reg Address of register in slave device to write to
+    /// \param writeData pointer to array of write commands
-    /// \param data Data to write to slave register
+    /// \param writeLen number of write commands
-    void masterTransmit(uint8_t addr, uint8_t reg, uint8_t data);
+    /// \param readData pointer to buffer to write received data to
+    /// \param readLen number of bytes to be read
+    void masterWriteRead(uint8_t addr,const uint8_t* writeData, size_t writeLen, uint8_t* readData, size_t readLen);
+
+    uint8_t masterWriteReadByte(uint8_t addr, const uint8_t* writeData, size_t writeLen);
+
+    /// Function to write an array of commands to an I2C device
+    /// \param addr Address of slave device
+    /// \param writeData Pointer to array of commands
+    /// \param writeLen Number of commands
+    void masterWrite(uint8_t addr, const uint8_t* writeData, uint8_t writeLen);
+
+    /// Function to read bytes from an I2C device
+    /// \param addr Address of slave device
+    /// \param readBuffer Pointer to buffer where data will be placed
+    /// \param bytesToRead Number of bytes to read
+    void masterRead(uint8_t addr, uint8_t* readBuffer, uint8_t bytesToRead);
 
-    ///
-    /// \param addr I2C address of slave device
-    /// \param reg Register to read data from
-    uint8_t masterReceive(uint8_t addr, uint8_t reg);
 
     //Manually set the clock configuration. Refer to your MCU's reference manual for examples
     void setClockConfig(uint8_t prescaler, uint8_t dataSetupTime, uint8_t dataHoldTime, uint8_t SCLHighPeriod, uint8_t SCLLowPeriod);

SHAL/Include/SHAL.h

@@ -11,5 +11,6 @@
 #include "SHAL_TIM.h"
 #include "SHAL_GPIO.h"
 #include "SHAL_UART.h"
+#include "SHAL_I2C.h"
 
 #endif

SHAL/Src/Core/SHAL_CORE.cpp

@@ -0,0 +1,42 @@
+//
+// Created by Luca on 9/15/2025.
+//
+
+#include "SHAL_CORE.h"
+
+void SHAL_init(){
+    systick_init(); //Just this for now
+}
+
+
+void systick_init(){
+    SysTick->CTRL = 0;           //Disable first
+    SysTick->LOAD = 0xFFFFFF;    //Max 24-bit
+    SysTick->VAL  = 0;           //Clear
+    SysTick->CTRL = SysTick_CTRL_CLKSOURCE_Msk | SysTick_CTRL_ENABLE_Msk;
+}
+
+
+void SHAL_delay_us(uint32_t us){
+    uint32_t ticks = us * (SystemCoreClock / 1000000U);
+    uint32_t start = SysTick->VAL;
+
+    //Calculate target value (may wrap around)
+    uint32_t target = (start >= ticks) ? (start - ticks) : (start + 0x01000000 - ticks);
+    target &= 0x00FFFFFF;
+
+    //Wait until we reach the target
+    if (start >= ticks) {
+        //No wraparound case
+        while (SysTick->VAL > target) {}
+    } else {
+        while (SysTick->VAL <= start) {} //Wait for wraparound
+        while (SysTick->VAL > target) {} //Wait for target
+    }
+}
+
+void SHAL_delay_ms(uint32_t ms){
+    while(ms-- > 0){
+        SHAL_delay_us(1000);
+    }
+}

SHAL/Src/Peripheral/I2C/SHAL_I2C.cpp

@@ -5,15 +5,21 @@
 #include "SHAL_I2C.h"
 #include "SHAL_GPIO.h"
 
+#include "SHAL_UART.h"
+
 void SHAL_I2C::init(I2C_Pair pair) volatile {
     m_I2CPair = pair;
 
-    SHAL_I2C_Pair I2CPair = getI2CPair(pair); //Get the UART_PAIR information to be initialized
+    SHAL_I2C_Pair I2CPair = getI2CPair(pair); //Get the I2C_PAIR information to be initialized
 
     //Get the SHAL_GPIO pins for this SHAL_I2C setup
     GPIO_Key SCL_Key = I2CPair.SCL_Key; //SCL pin
     GPIO_Key SDA_Key = I2CPair.SDA_Key; //SDA pin
 
+    SHAL_I2C_Enable_Reg pairI2CEnable = getI2CEnableReg(pair); //Register and mask to enable the I2C peripheral
+
+    *pairI2CEnable.reg &= ~pairI2CEnable.mask; //Enable I2C peripheral clock
+
     GET_GPIO(SCL_Key).setPinMode(PinMode::ALTERNATE_FUNCTION_MODE); //Implicitly initializes and enables GPIO bus
     GET_GPIO(SDA_Key).setPinMode(PinMode::ALTERNATE_FUNCTION_MODE);
 
@@ -30,13 +36,12 @@ void SHAL_I2C::init(I2C_Pair pair) volatile {
     GET_GPIO(SCL_Key).setInternalResistor(InternalResistorType::PULLUP);
     GET_GPIO(SDA_Key).setInternalResistor(InternalResistorType::PULLUP);
 
-    SHAL_I2C_Enable_Reg pairI2CEnable = getI2CEnableReg(pair); //Register and mask to enable the I2C peripheral
     SHAL_I2C_Reset_Reg pairI2CReset = getI2CResetReg(pair);
 
-    *pairI2CReset.reg |= pairI2CReset.mask; //Reset peripheral
     *pairI2CEnable.reg |= pairI2CEnable.mask; //Enable I2C peripheral clock
 
-    I2CPair.I2CReg->CR1 |= I2C_CR1_PE; //Enable I2C peripheral
+    *pairI2CReset.reg |= pairI2CReset.mask; //Reset peripheral
+    *pairI2CReset.reg &= ~pairI2CReset.mask; //Reset peripheral
 }
 
 void SHAL_I2C::setClockConfig(uint8_t prescaler, uint8_t dataSetupTime, uint8_t dataHoldTime, uint8_t SCLHighPeriod, uint8_t SCLLowPeriod) {
@@ -48,65 +53,82 @@ void SHAL_I2C::setClockConfig(uint8_t prescaler, uint8_t dataSetupTime, uint8_t
     *clockReg.reg |= (dataHoldTime << clockReg.dataHoldTime_offset);
     *clockReg.reg |= (SCLHighPeriod << clockReg.SCLHighPeriod_offset);
     *clockReg.reg |= (SCLLowPeriod << clockReg.SCLLowPeriod_offset);
+
+    getI2CPair(m_I2CPair).I2CReg->CR1 |= I2C_CR1_PE; //Enable I2C peripheral
 }
 
 void SHAL_I2C::setClockConfig(uint32_t configuration) {
     *getI2CTimerReg(m_I2CPair).reg = configuration;
+
+    getI2CPair(m_I2CPair).I2CReg->CR1 |= I2C_CR1_PE; //Enable I2C peripheral
 }
 
-void SHAL_I2C::masterTransmit(uint8_t addr, uint8_t reg, uint8_t data) {
+void SHAL_I2C::masterWriteRead(uint8_t addr,const uint8_t* writeData, size_t writeLen, uint8_t* readData, size_t readLen) {
 
     volatile I2C_TypeDef* I2CPeripheral = getI2CPair(m_I2CPair).I2CReg;
 
-    //Wait until not busy
+    if(!SHAL_WAIT_FOR_CONDITION_MS((I2CPeripheral->ISR & I2C_ISR_BUSY) == 0, 100)){
-    while (I2CPeripheral->ISR & I2C_ISR_BUSY);
+        SHAL_UART2.sendString("I2C timed out waiting for not busy\r\n");
+        return;
+    }
 
-    //Send start + slave address
+    //Write phase
-    I2CPeripheral->CR2 = (addr << 1) | (2 << I2C_CR2_NBYTES_Pos) | I2C_CR2_START | I2C_CR2_AUTOEND; //Pack bits in compliance with I2C format
+    if (writeLen > 0) {
+        //Configure: NBYTES = wlen, write mode, START
+        I2CPeripheral->CR2 = (addr << 1) | (writeLen << I2C_CR2_NBYTES_Pos) | I2C_CR2_START;
 
-    //Wait until TX ready
+        for (size_t i = 0; i < writeLen; i++) {
-    while (!(I2CPeripheral->ISR & I2C_ISR_TXIS));
+            if(!SHAL_WAIT_FOR_CONDITION_MS((I2CPeripheral->ISR & I2C_ISR_TXIS) != 0, 100)){
+                SHAL_UART2.sendString("I2C timed out waiting for TX\r\n");
+                return;
+            }
+            I2CPeripheral->TXDR = writeData[i];
+        }
 
-    //Send register address
+        //Wait until transfer complete
-    I2CPeripheral->TXDR = reg;
+        if(!SHAL_WAIT_FOR_CONDITION_MS((I2CPeripheral->ISR & I2C_ISR_TC) != 0, 100)){
+            SHAL_UART2.sendString("I2C timed out waiting for TC\r\n");
+            return;
+        }
+    }
 
-    //Wait until TX ready
+    //Read phase
-    while (!(I2CPeripheral->ISR & I2C_ISR_TXIS));
+    if (readLen > 0) {
 
-    //Send data to write to register
+        SHAL_UART2.sendString("Read initiated\r\n");
-    I2CPeripheral->TXDR = data;
+
+        I2CPeripheral->CR2 &= ~(I2C_CR2_NBYTES | I2C_CR2_SADD | I2C_CR2_RD_WRN);
+        I2CPeripheral->CR2 |= (addr << 1) |
+                              I2C_CR2_RD_WRN |
+                              (readLen << I2C_CR2_NBYTES_Pos) |
+                              I2C_CR2_START | I2C_CR2_AUTOEND;
+
+        for (size_t i = 0; i < readLen; i++) {
+            if(!SHAL_WAIT_FOR_CONDITION_MS((I2CPeripheral->ISR & I2C_ISR_RXNE) != 0 , 100)){
+                SHAL_UART2.sendString("I2C timed out waiting for RXNE\r\n");
+                return;
+            }
+            SHAL_UART2.sendString("Read byte");
+            readData[i] = static_cast<uint8_t>(I2CPeripheral->RXDR);
+        }
+    }
+    else{
+        I2CPeripheral->CR2 |= I2C_CR2_STOP;
+    }
 }
 
+void SHAL_I2C::masterWrite(uint8_t addr, const uint8_t *writeData, uint8_t writeLen) {
+    masterWriteRead(addr,writeData,writeLen,nullptr,0);
+}
 
-uint8_t SHAL_I2C::masterReceive(uint8_t addr, uint8_t reg) {
+void SHAL_I2C::masterRead(uint8_t addr, uint8_t *readBuffer, uint8_t bytesToRead) {
+    masterWriteRead(addr,nullptr,0,readBuffer,bytesToRead);
+}
 
-    volatile I2C_TypeDef* I2CPeripheral = getI2CPair(m_I2CPair).I2CReg;
+uint8_t SHAL_I2C::masterWriteReadByte(uint8_t addr, const uint8_t *writeData, size_t writeLen) {
-
+    uint8_t val = 0;
-    //Send register address with write
+    masterWriteRead(addr, writeData, writeLen, &val, 1);
-
+    return val;
-    //Wait for bus
-    while (I2CPeripheral->ISR & I2C_ISR_BUSY);
-
-    //Send start with I2C config
-    I2CPeripheral->CR2 = (addr << 1) | (1 << I2C_CR2_NBYTES_Pos) | I2C_CR2_START;
-
-    //Wait for transmit
-    while (!(I2CPeripheral->ISR & I2C_ISR_TXIS));
-
-    //Set address to read from
-    I2CPeripheral->TXDR = reg;
-
-    //Wait for transfer to complete
-    while (!(I2CPeripheral->ISR & I2C_ISR_TC));
-
-    //Restart in read mode, auto end
-    I2CPeripheral->CR2 = (addr << 1) | I2C_CR2_RD_WRN |
-                (1 << I2C_CR2_NBYTES_Pos) |
-                I2C_CR2_START | I2C_CR2_AUTOEND;
-
-    //Wait
-    while (!(I2C1->ISR & I2C_ISR_RXNE));
-    return (uint8_t)I2C1->RXDR;
 }
 
 SHAL_I2C& I2CManager::get(uint8_t I2CBus) {

SHAL/Src/main.cpp

@@ -1,10 +1,44 @@
 #include "SHAL.h"
 #include "stm32f0xx.h"
 
+#include <stdlib.h>
 
 void c3Interrupt(){
-    PIN(A5).toggle();
+    SHAL_UART2.sendString("Begin\r\n");
-    UART(2).sendString("New test");
+
+    uint8_t cmd[3] = {0xAC, 0x33, 0x00};
+    SHAL_I2C1.masterWrite(0x38, cmd, 3);
+
+    SHAL_delay_ms(100);
+
+    uint8_t dht_buf[7] = {0};
+
+    //Read 7 bytes (status + 5 data + CRC)
+    SHAL_I2C1.masterRead(0x38, dht_buf, 7);
+
+    //Parse humidity (20 bits)
+    uint32_t rawHumidity = ((uint32_t)dht_buf[1] << 12) |
+                           ((uint32_t)dht_buf[2] << 4) |
+                           ((uint32_t)dht_buf[3] >> 4);
+
+    uint32_t rawTemp = (((uint32_t)dht_buf[3] & 0x0F) << 16) |
+                       ((uint32_t)dht_buf[4] << 8) |
+                       ((uint32_t)dht_buf[5]);
+
+    // Use 64-bit intermediate to avoid overflow
+    uint32_t hum_hundredths = (uint32_t)(((uint64_t)rawHumidity * 10000ULL) >> 20);
+    int32_t temp_hundredths = (int32_t)((((uint64_t)rawTemp * 20000ULL) >> 20) - 5000);
+
+    char out[80];
+    sprintf(out, "rawH=0x%05lX rawT=0x%05lX\r\n",
+            (unsigned long)rawHumidity, (unsigned long)rawTemp);
+    SHAL_UART2.sendString(out);
+
+    // print as X.YY
+    sprintf(out, "Temp: %ld.%02ld C, Hum: %ld.%02ld %%\r\n",
+            (long)(temp_hundredths / 100), (long)(abs(temp_hundredths % 100)),
+            (long)(hum_hundredths / 100), (long)(hum_hundredths % 100));
+    SHAL_UART2.sendString(out);
 }
 
 void tim2Handler(){
@@ -13,10 +47,15 @@ void tim2Handler(){
 
 int main() {
 
+    SHAL_init();
+
     //Setup UART2 (used by nucleo devices for USB comms)
     SHAL_UART2.init(UART_Pair::Tx2A2_Rx2A3);
     SHAL_UART2.begin(115200);
 
+    SHAL_I2C1.init(I2C_Pair::SCL1B6_SDA1B7);
+    SHAL_I2C1.setClockConfig(0x2000090E);
+
     //Use pin C3 to trigger a function on external interrupt
     PIN(C3).useAsExternalInterrupt(TriggerMode::RISING_EDGE,c3Interrupt);
 
@@ -27,6 +66,25 @@ int main() {
     PIN(A4).setPinMode(PinMode::OUTPUT_MODE);
     PIN(A5).setPinMode(PinMode::OUTPUT_MODE);
 
+
+
+    SHAL_delay_ms(3000); //Wait 100 ms from datasheet
+
+    uint8_t cmd = 0x71;
+    uint8_t status = 0;
+
+    SHAL_I2C1.masterWriteRead(0x38, &cmd, 1, &status, 1);
+
+    char statusString[32];
+    sprintf(statusString, "Status = 0x%02X\r\n", status);
+    SHAL_UART2.sendString(statusString);
+
+
+    SHAL_delay_ms(10);
+
+    c3Interrupt();
+    //End setup
+
     while (true) {
     	__WFI();
     }