From 65dc19b01a6b816b30a49d9aa924c6c301557828 Mon Sep 17 00:00:00 2001
From: robert-hh <robert@hammelrath.com>
Date: Sat, 26 Aug 2023 10:43:09 +0200
Subject: [PATCH] samd: Change the init sequence for adc_timed() and
 dac_timed().

To leave no half-initialized device if init fails.

Signed-off-by: robert-hh <robert@hammelrath.com>
---
 ports/samd/machine_adc.c | 8 +++++---
 ports/samd/machine_dac.c | 6 +++---
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/ports/samd/machine_adc.c b/ports/samd/machine_adc.c
index efaf2b708a59..8eb3fcc72a08 100644
--- a/ports/samd/machine_adc.c
+++ b/ports/samd/machine_adc.c
@@ -267,14 +267,14 @@ static void machine_adc_read_timed(mp_obj_t self_in, mp_obj_t values, mp_obj_t f
     mp_get_buffer_raise(values, &src, MP_BUFFER_READ);
     if (src.len >= 2) {
         int freq = mp_obj_get_int(freq_in);
+        if (self->tc_index == -1) {
+            self->tc_index = allocate_tc_instance();
+        }
         if (self->dma_channel == -1) {
             self->dma_channel = allocate_dma_channel();
             dma_init();
             dma_register_irq(self->dma_channel, adc_irq_handler);
         }
-        if (self->tc_index == -1) {
-            self->tc_index = allocate_tc_instance();
-        }
         // Set the reference voltage. Default: external AREFA.
         adc->REFCTRL.reg = adc_vref_table[self->vref];
         // Set Input channel and resolution
@@ -330,6 +330,8 @@ static void machine_adc_read_timed(mp_obj_t self_in, mp_obj_t values, mp_obj_t f
         adc->SWTRIG.bit.START = 1;
         while (adc->INTFLAG.bit.RESRDY == 0) {
         }
+        // Wait a little bit allowing the ADC to settle.
+        mp_hal_delay_us(15);
 
         dma_desc[self->dma_channel].BTCTRL.reg =
             DMAC_BTCTRL_VALID | DMAC_BTCTRL_BLOCKACT_NOACT |
diff --git a/ports/samd/machine_dac.c b/ports/samd/machine_dac.c
index 21b0e67d4d6a..425c01f4a809 100644
--- a/ports/samd/machine_dac.c
+++ b/ports/samd/machine_dac.c
@@ -287,14 +287,14 @@ static mp_obj_t dac_write_timed(size_t n_args, const mp_obj_t *args) {
     }
     if (src.len >= 2) {
         int freq = mp_obj_get_int(args[2]);
+        if (self->tc_index == -1) {
+            self->tc_index = allocate_tc_instance();
+        }
         if (self->dma_channel == -1) {
             self->dma_channel = allocate_dma_channel();
             dma_init();
             dma_register_irq(self->dma_channel, dac_irq_handler);
         }
-        if (self->tc_index == -1) {
-            self->tc_index = allocate_tc_instance();
-        }
         // Configure TC; no need to check the return value
         configure_tc(self->tc_index, freq, 0);
         self->busy = true;