Getting closer to i2c things.

src/main.rs

@@ -3,6 +3,7 @@
 
 use core::ptr::read_volatile;
 
+use cortex_m::peripheral;
 // pick a panicking behavior
 use panic_halt as _; // you can put a breakpoint on `rust_begin_unwind` to catch panics
 // use panic_abort as _; // requires nightly
@@ -13,9 +14,9 @@ use cortex_m_rt::{entry, exception};
 use cortex_m_semihosting::hprintln;
 use stm32f1::stm32f103;
 
-static mut SYS_TICK: u64 = 0;
+static mut SYS_TICK: u32 = 0;
 
-fn get_sys_tick() -> u64 {
+fn get_sys_tick() -> u32 {
     unsafe { read_volatile(&raw const SYS_TICK) }
 }
 
@@ -33,13 +34,34 @@ fn toggle_mcu_led(peripherals: &mut stm32f103::Peripherals) {
     });
 }
 
+fn i2c1_write(i2c: &stm32f103::I2C1, addr: &u8, data: &[u8]) {
+    i2c.cr1.modify(|_,w| w.start().set_bit());
 
+    while i2c.sr1.read().sb().bit_is_clear() {}
+
+    i2c.dr.write(|w| w.dr().bits(*addr));
+
+    while i2c.sr1.read().addr().bit_is_clear() {}
+    
+    // 5. Clear the ADDR flag by reading SR2.
+    let _ = i2c.sr2.read();
+
+    for byte in data {
+        i2c.dr.write(|w| w.dr().bits(*byte));
+        while i2c.sr1.read().tx_e().bit_is_clear() {}
+    }
+
+    while i2c.sr1.read().btf().bit_is_clear() {}
+
+    i2c.cr1.modify(|_,w| w.stop().set_bit());
+}
 
 #[entry]
 fn main() -> ! {
     let mut peripherals = stm32f103::Peripherals::take().unwrap();
     let mut core_peripherals = cortex_m::Peripherals::take().unwrap();
 
+
     // Enable Cortex-M SysTick
     peripherals.STK.ctrl.modify(|_,w| w.tickint().set_bit());   // Enable Systick Interrupt
     core_peripherals.SYST.set_reload(1_000 - 1);                        // Set period to 1ms
@@ -54,11 +76,25 @@ fn main() -> ! {
     peripherals.GPIOA.odr.modify(|_, w| w.odr3().high());
 
     // Init i2c
-    // 8MHz SYSCLOCK / 16 = 500khz i2c bus
+    // Configure i2c clock
-    peripherals.RCC.cfgr.modify(|_, w| w.ppre1().div16());
+    peripherals.RCC.apb2enr.modify(|_,w| w.iopben().enabled());
+    peripherals.RCC.cfgr.modify(|_, w| w.ppre1().div4());
     peripherals.RCC.apb1enr.modify(|_, w| w.i2c1en().enabled());
-    peripherals.RCC.apb1enr.modify(|_, w| w.i2c2en().enabled());
+    
+    // Set GPIO pin configurations
+    peripherals.GPIOB.crl.modify(|_,w| w.mode6().output50());
+    peripherals.GPIOB.crl.modify(|_,w| w.mode7().output50());
+
+    peripherals.GPIOB.crl.modify(|_,w| w.cnf6().alt_open_drain());
+    peripherals.GPIOB.crl.modify(|_,w| w.cnf7().alt_open_drain());
+
+    // Configure peripheral
+    peripherals.I2C1.cr2.modify(|_,w| unsafe { w.freq().bits(0x02) });
+    peripherals.I2C1.trise.write(|w| w.trise().bits(0x09));
     peripherals.I2C1.cr1.modify(|_,w| w.pe().enabled());
+    peripherals.I2C1.ccr.modify(|_,w| w.f_s().standard());
+    peripherals.I2C1.ccr.modify(|_,w| unsafe { w.ccr().bits(0x04) });
+    
 
     let mut timer_ms = 500;
 
@@ -69,6 +105,10 @@ fn main() -> ! {
         {
             toggle_mcu_led(&mut peripherals);
             timer_ms = current_value + 500;
+            let addr: u8 = 0x0a;
+            let data: [u8;4] = [0x01, 0x02, 0x03, 0x04];
+
+            i2c1_write(&peripherals.I2C1, &addr, &data);
         }
     }
 }