From 44132e00fe72eec0a84e70dc96f8bef52cae749f Mon Sep 17 00:00:00 2001
From: Thomas Kolb <cfr34k-git@tkolb.de>
Date: Wed, 4 Jan 2023 23:33:52 +0100
Subject: [PATCH] get_adc_channel_blocking: pass everything by-value to make it
 compile
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Still not really the final solution…
---
 src/main.rs | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 5ac4e64..4db7494 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -19,7 +19,6 @@ use panic_halt as _;
 use rp2040_hal as hal;
 
 // Some traits we need
-use cortex_m::singleton;
 use embedded_hal::PwmPin;
 use fugit::RateExtU32;
 use rp2040_hal::clocks::Clock;
@@ -54,24 +53,26 @@ const HIGH: u16 = 25000;
 /// if your board has a different frequency
 const XTAL_FREQ_HZ: u32 = 12_000_000u32;
 
-fn get_adc_channel_blocking<BIDI, WORD, E>(dma: &hal::dma::Channels, spi: &mut BIDI, cs_pin: &dyn embedded_hal::digital::v2::OutputPin<Error = E>) -> u16
+fn get_adc_channel_blocking<S, E>(dma: hal::dma::Channels, spi: rp2040_hal::Spi<rp2040_hal::spi::Enabled, S, 8>, cs_pin: &mut dyn embedded_hal::digital::v2::OutputPin<Error = E>) -> u16
 where
-    BIDI: hal::dma::ReadTarget<ReceivedWord = WORD> + hal::dma::WriteTarget<TransmittedWord = WORD>,
+    S: hal::spi::SpiDevice,
     E: core::fmt::Debug
 {
-    let mut tx_buf: [u8; 3] = [0x06, 0x40, 0x00];
-    let mut rx_buf: [u8; 3] = [0; 3];
+    static TX_BUF: [u8; 3] = [0x06, 0x40, 0x00];
+    static mut RX_BUF: [u8; 3] = [0; 3];
 
     // clear chip select
     cs_pin.set_low().unwrap();
 
     // Use BidirectionalConfig to simultaneously write to spi from tx_buf and read into rx_buf
-    let transfer = bidirectional::Config::new((dma.ch0, dma.ch1), &tx_buf, spi, &mut rx_buf).start();
-    // Wait for both DMA channels to finish
-    let ((_ch0, _ch1), tx_buf, _spi, rx_buf) = transfer.wait();
-    cs_pin.set_high().unwrap();
+    unsafe { // necessary due to mutable-static use
+        let transfer = bidirectional::Config::new((dma.ch0, dma.ch1), &TX_BUF, spi, &mut RX_BUF).start();
+        // Wait for both DMA channels to finish
+        let ((_ch0, _ch1), _tx_buf, _spi, _rx_buf) = transfer.wait();
+        cs_pin.set_high().unwrap();
 
-    (((rx_buf[1] & 0x0F) as u16) << 8) | rx_buf[2] as u16
+        (((RX_BUF[1] & 0x0F) as u16) << 8) | RX_BUF[2] as u16
+    }
 }
 
 /// Entry point to our bare-metal application.
@@ -193,7 +194,7 @@ fn main() -> ! {
     //let tx_buf = singleton!(: [u8; 3] = [0x06, 0x40, 0x00]).unwrap();
     //let rx_buf = singleton!(: [u8; 3] = [0; 3]).unwrap();
 
-    let adc_value = get_adc_channel_blocking(&dma, &mut spi, &spi_cs);
+    let adc_value = get_adc_channel_blocking(dma, spi, &mut spi_cs);
 
     {
         let data: String<16> = String::from(adc_value);