From a0799bf270010f4e91b0c3eebe487d8bc6fb54fc Mon Sep 17 00:00:00 2001
From: Chen Yuheng <1016867898@qq.com>
Date: Thu, 27 Jun 2024 17:04:26 +0800
Subject: [PATCH] Add adc oversampling support

---
 embassy-stm32/src/adc/v3.rs                  | 15 +++++++
 examples/stm32g0/src/bin/adc_oversampling.rs | 43 ++++++++++++++++++++
 2 files changed, 58 insertions(+)
 create mode 100644 examples/stm32g0/src/bin/adc_oversampling.rs

diff --git a/embassy-stm32/src/adc/v3.rs b/embassy-stm32/src/adc/v3.rs
index 398c57a92..bf7ad242b 100644
--- a/embassy-stm32/src/adc/v3.rs
+++ b/embassy-stm32/src/adc/v3.rs
@@ -277,6 +277,21 @@ impl<'d, T: Instance> Adc<'d, T> {
         val
     }
 
+    #[cfg(any(adc_g0, adc_u0))]
+    pub fn set_oversampling_shift(&mut self, shift: u8) {
+        T::regs().cfgr2().modify(|reg| reg.set_ovss(shift));
+    }
+
+    #[cfg(any(adc_g0, adc_u0))]
+    pub fn set_oversampling_ratio(&mut self, ratio: u8) {
+        T::regs().cfgr2().modify(|reg| reg.set_ovsr(ratio));
+    }
+
+    #[cfg(any(adc_g0, adc_u0))]
+    pub fn oversampling_enable(&mut self, enable: bool) {
+        T::regs().cfgr2().modify(|reg| reg.set_ovse(enable));
+    }
+
     fn set_channel_sample_time(_ch: u8, sample_time: SampleTime) {
         cfg_if! {
             if #[cfg(any(adc_g0, adc_u0))] {
diff --git a/examples/stm32g0/src/bin/adc_oversampling.rs b/examples/stm32g0/src/bin/adc_oversampling.rs
new file mode 100644
index 000000000..3c31eb206
--- /dev/null
+++ b/examples/stm32g0/src/bin/adc_oversampling.rs
@@ -0,0 +1,43 @@
+//! adc oversampling example
+//!
+//! This example uses adc oversampling to achieve 16bit data
+
+#![no_std]
+#![no_main]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_stm32::adc::{Adc, SampleTime};
+use embassy_time::Timer;
+use {defmt_rtt as _, panic_probe as _};
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let p = embassy_stm32::init(Default::default());
+    info!("Adc oversample test");
+
+    let mut adc = Adc::new(p.ADC1);
+    adc.set_sample_time(SampleTime::CYCLES1_5);
+    let mut pin = p.PA1;
+
+    // From https://www.st.com/resource/en/reference_manual/rm0444-stm32g0x1-advanced-armbased-32bit-mcus-stmicroelectronics.pdf
+    // page373 15.8 Oversampler
+    // Table 76. Maximum output results vs N and M. Grayed values indicates truncation
+    // 0x00 oversampling ratio X2
+    // 0x01 oversampling ratio X4
+    // 0x02 oversampling ratio X8
+    // 0x03 oversampling ratio X16
+    // 0x04 oversampling ratio X32
+    // 0x05 oversampling ratio X64
+    // 0x06 oversampling ratio X128
+    // 0x07 oversampling ratio X256
+    adc.set_oversampling_ratio(0x03);
+    adc.set_oversampling_shift(0b0000);
+    adc.oversampling_enable(true);
+
+    loop {
+        let v = adc.read(&mut pin);
+        info!("--> {} ", v); //max 65520 = 0xFFF0
+        Timer::after_millis(100).await;
+    }
+}