diff --git a/ports/atmel-samd/audio_dma.c b/ports/atmel-samd/audio_dma.c
index 227a2e1881..b468acf51e 100644
--- a/ports/atmel-samd/audio_dma.c
+++ b/ports/atmel-samd/audio_dma.c
@@ -274,11 +274,16 @@ audio_dma_result audio_dma_setup_playback(audio_dma_t* dma,
         MP_STATE_PORT(playing_audio)[dma->dma_channel] = dma->sample;
     }
 
-    dma->beat_size = 1;
-    dma->bytes_per_sample = 1;
+
     if (audiosample_bits_per_sample(sample) == 16) {
         dma->beat_size = 2;
         dma->bytes_per_sample = 2;
+    } else {
+        dma->beat_size = 1;
+        dma->bytes_per_sample = 1;
+        if (single_channel) {
+            output_register_address += 1;
+        }
     }
     // Transfer both channels at once.
     if (!single_channel && audiosample_channel_count(sample) == 2) {
diff --git a/ports/atmel-samd/common-hal/audiobusio/PDMIn.c b/ports/atmel-samd/common-hal/audiobusio/PDMIn.c
index 7788335d1c..8cf86421c9 100644
--- a/ports/atmel-samd/common-hal/audiobusio/PDMIn.c
+++ b/ports/atmel-samd/common-hal/audiobusio/PDMIn.c
@@ -371,7 +371,12 @@ uint32_t common_hal_audiobusio_pdmin_record_to_buffer(audiobusio_pdmin_obj_t* se
     setup_dma(self, output_buffer_length, dma_descriptor(dma_channel), &second_descriptor,
               words_per_buffer, words_per_sample, first_buffer, second_buffer);
 
-    dma_configure(dma_channel, I2S_DMAC_ID_RX_0, true);
+    uint8_t trigger_source = I2S_DMAC_ID_RX_0;
+    #ifdef SAMD21
+    trigger_source += self->serializer;
+    #endif
+
+    dma_configure(dma_channel, trigger_source, true);
     init_event_channel_interrupt(event_channel, CORE_GCLK, EVSYS_ID_GEN_DMAC_CH_0 + dma_channel);
     dma_enable_channel(dma_channel);
 
diff --git a/ports/atmel-samd/shared_dma.c b/ports/atmel-samd/shared_dma.c
index 88c89abeeb..a7c27a46eb 100644
--- a/ports/atmel-samd/shared_dma.c
+++ b/ports/atmel-samd/shared_dma.c
@@ -99,6 +99,8 @@ void dma_enable_channel(uint8_t channel_number) {
     common_hal_mcu_disable_interrupts();
     /** Select the DMA channel and clear software trigger */
     DMAC->CHID.reg = DMAC_CHID_ID(channel_number);
+    // Clear any previous interrupts.
+    DMAC->CHINTFLAG.reg = DMAC_CHINTFLAG_MASK;
     DMAC->CHCTRLA.bit.ENABLE = true;
     common_hal_mcu_enable_interrupts();
     #endif
@@ -106,6 +108,8 @@ void dma_enable_channel(uint8_t channel_number) {
     #ifdef SAMD51
     DmacChannel* channel = &DMAC->Channel[channel_number];
     channel->CHCTRLA.bit.ENABLE = true;
+    // Clear any previous interrupts.
+    channel->CHINTFLAG.reg = DMAC_CHINTFLAG_MASK;
     #endif
 }