max1968: Fix ADC+DMA does not start converting bug

src/thermostat/max1968.rs

@@ -1,15 +1,14 @@
 use crate::thermostat::ad5680;
 use fugit::KilohertzU32;
-use stm32_eth::stm32::{ADC2, DMA2};
-
 use stm32f4xx_hal::{
     adc::{config::{self, AdcConfig}, Adc}, 
     dma::{config::DmaConfig, PeripheralToMemory, Stream2, StreamsTuple, Transfer as DMA_Transfer}, 
     gpio::{gpioa::*, gpiob::*, gpioc::*, Alternate, Analog, Output, PushPull}, 
     hal::{self, blocking::spi::Transfer, digital::v2::OutputPin}, 
-    pac::{ADC1, SPI1, TIM4}, 
+    pac::{ADC1, ADC2, DMA2, SPI1, TIM4, Peripherals, NVIC}, 
     spi::{NoMiso, Spi, TransferModeNormal}, 
-    timer::pwm::PwmChannel
+    timer::pwm::PwmChannel,
+    interrupt
 };
 
 use uom::si::{
@@ -75,10 +74,14 @@ pub struct MAX1968PinSet<C: ChannelPins> {
 type DacSpi = Spi<SPI1, (PB3<Alternate<5>>, NoMiso, PB5<Alternate<5>>), TransferModeNormal>;
 type DacSync = PB4<Output<PushPull>>;
 
+static mut DMA_TRANSFER_COMPLETE: bool = true;
+
 pub struct MAX1968 {
     pub phy: MAX1968Phy<Channel0>,
     pub pins_adc: Adc<ADC1>,
     pub dma_adc: DMA_Transfer<Stream2<DMA2>, 1, Adc<ADC2>, PeripheralToMemory, &'static mut [u16; 16]>,
+    prev_vtec_volt: ElectricPotential,
+    prev_itec_volt: ElectricPotential,
 }
 
 pub enum PwmPinsEnum {
@@ -155,50 +158,57 @@ impl MAX1968 {
         let dma_adc : DMA_Transfer<Stream2<DMA2>, 1, Adc<ADC2>, PeripheralToMemory, &'static mut [u16; 16]>;
         unsafe {
             dma_adc = DMA_Transfer::init_peripheral_to_memory(dma.2, pins_adc2, &mut ADC2_FIRST_BUFFER, None, dma_config);
+            NVIC::unmask(interrupt::DMA2_STREAM2);
         }
 
         MAX1968 {
             phy: phy_ch0,
             pins_adc: pins_adc1,
             dma_adc: dma_adc,
+            prev_vtec_volt: ElectricPotential::new::<millivolt>(0.0), 
+            prev_itec_volt: ElectricPotential::new::<millivolt>(0.0), 
         }
     }
 
     pub fn dma_adc_start_conversion(&mut self){
-        self.dma_adc.clear_interrupts();
-        self.dma_adc.start(|adc| {
-            adc.clear_end_of_conversion_flag();
-            adc.start_conversion();
-        });
+        if unsafe {DMA_TRANSFER_COMPLETE} {
+            unsafe { DMA_TRANSFER_COMPLETE = false; }
+            self.dma_adc.start(|adc| {       
+                adc.clear_end_of_conversion_flag();
+                adc.start_conversion();
+            });
+        }  
     }
 
     pub fn get_tec_readings(&mut self) -> (ElectricPotential, ElectricPotential) {
-        self.dma_adc.clear_interrupts();
-        let buffer: &[u16; 16];
-        unsafe{
-            (buffer, _) = self.dma_adc
-                .next_transfer(&mut ADC2_LOCAL_BUFFER)
-                .unwrap();
-        }
-        
-        let sample_to_millivolts = self.dma_adc.peripheral().make_sample_to_millivolts();
-        let mut itec: u16 = 0;
-        for data in buffer.into_iter().step_by(2){
-            itec += *data;
-        }
-        itec = itec >> 3;
+        if unsafe { DMA_TRANSFER_COMPLETE } {
+            let buffer: &[u16; 16];
+            unsafe {
+                (buffer, _) = self.dma_adc
+                    .next_transfer(&mut ADC2_LOCAL_BUFFER)
+                    .unwrap();
+            }
+            
+            let sample_to_millivolts = self.dma_adc.peripheral().make_sample_to_millivolts();
+            let mut itec: u16 = 0;
+            for data in buffer.into_iter().step_by(2) {
+                itec += *data;
+            }
+            itec = itec >> 3;
 
-        let mut vtec: u16 = 0;
-        for data in buffer.into_iter().skip(1).step_by(2){
-            vtec += *data;
-        }
-        vtec = vtec >> 3;
+            let mut vtec: u16 = 0;
+            for data in buffer.into_iter().skip(1).step_by(2) {
+                vtec += *data;
+            }
+            vtec = vtec >> 3;
 
-        unsafe {
-            ADC2_LOCAL_BUFFER = *buffer;
+            unsafe {
+                ADC2_LOCAL_BUFFER = *buffer;
+            }
+            self.prev_vtec_volt = ElectricPotential::new::<millivolt>(sample_to_millivolts(vtec) as f32);
+            self.prev_itec_volt = ElectricPotential::new::<millivolt>(sample_to_millivolts(itec) as f32);
         }
-
-        (ElectricPotential::new::<millivolt>(sample_to_millivolts(vtec) as f32), ElectricPotential::new::<millivolt>(sample_to_millivolts(itec) as f32))
+        (self.prev_vtec_volt, self.prev_itec_volt)
     }
 
     // Return the calibrated VDDA Voltage
@@ -292,3 +302,20 @@ impl MAX1968 {
     }
 
 }
+
+#[interrupt]
+fn DMA2_STREAM2(){
+    cortex_m::interrupt::free(|_| {
+            unsafe {
+                // Clear all DMA2_STREAM2 interrupt flags
+                Peripherals::steal().DMA2.lifcr.write(|w| w
+                    .ctcif2().set_bit()
+                    .cdmeif2().set_bit()
+                    .chtif2().set_bit()
+                    .cteif2().set_bit()
+                );
+                DMA_TRANSFER_COMPLETE = true;
+            }
+        }
+    )
+}