adafruit · dhalbert · Jun 11, 2025 · Jun 2, 2025 · Jun 2, 2025 · Jun 10, 2025
diff --git a/ports/espressif/common-hal/pulseio/PulseIn.c b/ports/espressif/common-hal/pulseio/PulseIn.c
@@ -80,8 +80,9 @@ void common_hal_pulseio_pulsein_construct(pulseio_pulsein_obj_t *self, const mcu
     }
     // We add one to the maxlen version to ensure that two symbols at lease are
     // captured because we may skip the first portion of a symbol.
-    self->raw_symbols_size = MIN(64, maxlen / 2 + 1) * sizeof(rmt_symbol_word_t);
-    self->raw_symbols = (rmt_symbol_word_t *)m_malloc_without_collect(self->raw_symbols_size);
+    self->raw_symbols_size = (maxlen / 2 + 1) * sizeof(rmt_symbol_word_t);
+    // RMT DMA mode cannot access PSRAM -> ensure raw_symbols is in internal ram
+    self->raw_symbols = (rmt_symbol_word_t *)port_malloc(self->raw_symbols_size, true);
     if (self->raw_symbols == NULL) {
         m_free(self->buffer);
         m_malloc_fail(self->raw_symbols_size);
@@ -109,17 +110,26 @@ void common_hal_pulseio_pulsein_construct(pulseio_pulsein_obj_t *self, const mcu
         .clk_src = RMT_CLK_SRC_DEFAULT,
         // 2 us resolution so we can capture 65ms pulses. The RMT period is only 15 bits.
         .resolution_hz = 1000000 / 2,
-        .mem_block_symbols = SOC_RMT_MEM_WORDS_PER_CHANNEL,
+        .mem_block_symbols = self->raw_symbols_size,
+        .flags.with_dma = 1
     };
-    // If we fail here, the buffers allocated above will be garbage collected.
-    CHECK_ESP_RESULT(rmt_new_rx_channel(&config, &self->channel));
+    // If we fail here, the self->buffer will be garbage collected.
+    esp_err_t result = rmt_new_rx_channel(&config, &self->channel);
+    if (result != ESP_OK) {
+        port_free(self->raw_symbols);
+        raise_esp_error(result);
+    }
 
     rmt_rx_event_callbacks_t rx_callback = {
         .on_recv_done = _done_callback
     };
     rmt_rx_register_event_callbacks(self->channel, &rx_callback, self);
     rmt_enable(self->channel);
-    rmt_receive(self->channel, self->raw_symbols, self->raw_symbols_size, &rx_config);
+    result = rmt_receive(self->channel, self->raw_symbols, self->raw_symbols_size, &rx_config);
+    if (result != ESP_OK) {
+        port_free(self->raw_symbols);
+        raise_esp_error(result);
+    }
 }
 
 bool common_hal_pulseio_pulsein_deinited(pulseio_pulsein_obj_t *self) {

diff --git a/ports/espressif/supervisor/port.c b/ports/espressif/supervisor/port.c
@@ -304,18 +304,18 @@ void port_heap_init(void) {
 }
 
 void *port_malloc(size_t size, bool dma_capable) {
-    size_t caps = MALLOC_CAP_8BIT;
     if (dma_capable) {
-        caps |= MALLOC_CAP_DMA;
+        // SPIRAM is not DMA-capable, so don't bother to ask for it.
+        return heap_caps_malloc(size, MALLOC_CAP_8BIT | MALLOC_CAP_DMA);
     }
 
     void *ptr = NULL;
-    // Try SPIRAM first when available.
+    // Try SPIRAM first if available.
     #ifdef CONFIG_SPIRAM
-    ptr = heap_caps_malloc(size, caps | MALLOC_CAP_SPIRAM);
+    ptr = heap_caps_malloc(size, MALLOC_CAP_8BIT | MALLOC_CAP_SPIRAM);
     #endif
     if (ptr == NULL) {
-        ptr = heap_caps_malloc(size, caps);
+        ptr = heap_caps_malloc(size, MALLOC_CAP_8BIT);
     }
     return ptr;
 }