added pio-based rotary encoder reading.

Cargo.toml

@@ -20,6 +20,8 @@ panic-probe = { version = "0.3", features = ["print-defmt"] }
 rp-pico = "0.8"
 max31855 = "0.1.0"
 hd44780-driver = "0.4.0"
+pio-proc = "0.2"
+pio = "0.2"
 
 # cargo build/run
 [profile.dev]

src/encoder.pio

@@ -0,0 +1,51 @@
+; from https://github.com/GitJer/Rotary_encoder/blob/master/pio_rotary_encoder.pio
+.program pio_rotary_encoder
+.wrap_target
+.origin 0        ; The jump table has to start at 0
+                 ; it contains the correct jumps for each of the 16
+                 ; combination of 4 bits formed by A'B'AB
+                 ; A = current reading of pin_A of the rotary encoder
+                 ; A' = previous reading of pin_A of the rotary encoder
+                 ; B = current reading of pin_B of the rotary encoder
+                 ; B' = previous reading of pin_B of the rotary encoder
+    jmp read     ; 0000 = from 00 to 00 = no change in reading
+    jmp CW       ; 0001 = from 00 to 01 = clockwise rotation
+    jmp CCW      ; 0010 = from 00 to 10 = counter clockwise rotation
+    jmp read     ; 0011 = from 00 to 11 = error
+
+    jmp CCW      ; 0100 = from 01 to 00 = counter clockwise rotation
+    jmp read     ; 0101 = from 01 to 01 = no change in reading
+    jmp read     ; 0110 = from 01 to 10 = error
+    jmp CW       ; 0111 = from 01 to 11 = clockwise rotation
+
+    jmp CW       ; 1000 = from 10 to 00 = clockwise rotation
+    jmp read     ; 1001 = from 10 to 01 = error
+    jmp read     ; 1010 = from 10 to 10 = no change in reading
+    jmp CCW      ; 1011 = from 10 to 11 = counter clockwise rotation
+
+    jmp read     ; 1100 = from 11 to 00 = error
+    jmp CCW      ; 1101 = from 11 to 01 = counter clockwise rotation
+    jmp CW       ; 1110 = from 11 to 10 = clockwise rotation
+    jmp read     ; 1111 = from 11 to 11 = no change in reading
+
+pc_start:        ; this is the entry point for the program
+    in pins 2    ; read the current values of A and B and use
+                 ; them to initialize the previous values (A'B')
+read:
+    mov osr isr  ; the OSR is (after the next instruction) used to shift
+                 ; the two bits with the previous values into the ISR
+    out isr 2    ; shift the previous value into the ISR. This also sets
+                 ; all other bits in the ISR to 0
+    in pins 2    ; shift the current value into the ISR
+                 ; the 16 LSB of the ISR now contain 000000000000A'B'AB
+                 ; this represents a jmp instruction to the address A'B'AB
+    mov exec isr ; do the jmp encoded in the ISR
+CW:              ; a clockwise rotation was detected
+    irq 0        ; signal a clockwise rotation via an IRQ
+    jmp read     ; jump to reading the current values of A and B
+CCW:             ; a counter clockwise rotation was detected
+    irq 1        ; signal a counter clockwise rotation via an IRQ
+;    jmp read    ; jump to reading the current values of A and B.
+                 ; the jmp isn't needed because of the .wrap, and the first
+                 ; statement of the program happens to be a jmp read
+.wrap

src/main.rs

@@ -28,14 +28,15 @@ mod app {
                     Gpio0, Gpio1, Gpio14, Gpio16, Gpio17, Gpio18, Gpio19, Gpio2, Gpio20, Gpio21,
                     Gpio25, Gpio3, Gpio4, Gpio5,
                 },
-                FunctionSio, FunctionSpi, FunctionUart, Pin, PullDown, SioOutput,
+                FunctionPio0, FunctionSio, FunctionSpi, FunctionUart, Pin, PullDown, SioOutput,
             },
+            pio::PIOExt,
             sio::Sio,
             spi::{self, Spi},
             uart::{self, UartConfig, UartPeripheral},
             watchdog::Watchdog,
         },
-        pac::{SPI0, UART0},
+        pac::{self, SPI0, UART0},
         Pins,
     };
 
@@ -119,6 +120,7 @@ mod app {
     #[init]
     fn init(mut ctx: init::Context) -> (Shared, Local, init::Monotonics) {
         let mut watchdog = Watchdog::new(ctx.device.WATCHDOG);
+        let mut pac = pac::Peripherals::take().unwrap();
         let sio = Sio::new(ctx.device.SIO);
 
         // External high-speed crystal on the pico board is 12Mhz
@@ -212,6 +214,25 @@ mod app {
         )
         .unwrap();
 
+        let rotary_clk: Pin<_, FunctionPio0, _> = pins.gpio11.into_function();
+        let rotary_clk_id = rotary_clk.id().num;
+        let rotary_dt: Pin<_, FunctionPio0, _> = pins.gpio12.into_function();
+        let rotary_dt_id = rotary_dt.id().num;
+        let program = pio_proc::pio_file!("src/encoder.pio");
+
+        let (mut pio, sm0, _, _, _) = pac.PIO0.split(&mut pac.RESETS);
+        pio.irq0().enable_sm_interrupt(0);
+        pio.irq1().enable_sm_interrupt(1);
+        let installed = pio.install(&program.program).unwrap();
+        let (mut sm, _, _) = rp_pico::hal::pio::PIOBuilder::from_program(installed)
+            .set_pins(rotary_clk_id, 2)
+            .build(sm0);
+        sm.set_pindirs([
+            (rotary_clk_id, rp_pico::hal::pio::PinDir::Output),
+            (rotary_dt_id, rp_pico::hal::pio::PinDir::Output),
+        ]);
+        sm.start();
+
         let mono = Rp2040Mono::new(ctx.device.TIMER);
 
         heartbeat::spawn().unwrap();
@@ -234,6 +255,22 @@ mod app {
         )
     }
 
+    #[task(binds = PIO0_IRQ_0, shared = [target_temp])]
+    fn inc_target(mut ctx: inc_target::Context) {
+        ctx.shared.target_temp.lock(|t| {
+            *t += 1.0;
+        });
+        update_display::spawn().unwrap();
+    }
+
+    #[task(binds = PIO0_IRQ_1, shared = [target_temp])]
+    fn dec_target(mut ctx: dec_target::Context) {
+        ctx.shared.target_temp.lock(|t| {
+            *t -= 1.0;
+        });
+        update_display::spawn().unwrap();
+    }
+
     #[task(local = [thermocouple], shared = [recent_temp, uart])]
     fn read_temp(mut ctx: read_temp::Context) {
         match ctx.local.thermocouple.read_temp() {