stmhal: Add ADC function to read data at a given frequency.

Reads ADC values into a bytearray (or similar) at a fixed rate.  Needs a
better name and improved API.  Also fix up DAC dma function (which also
needs a better name and API).

1 files changed, 32 insertions, 0 deletions

diff --git a/stmhal/adc.c b/stmhal/adc.c
index 8a1c23c4f..dafa3f7bc 100644
--- a/stmhal/adc.c
+++ b/stmhal/adc.c
@@ -11,6 +11,7 @@
 #include "adc.h"
 #include "pin.h"
 #include "build/pins.h"
+#include "timer.h"
 
 // Usage Model:
 //
@@ -162,8 +163,39 @@ STATIC mp_obj_t adc_read(mp_obj_t self_in) {
 
 STATIC MP_DEFINE_CONST_FUN_OBJ_1(adc_read_obj, adc_read);
 
+STATIC mp_obj_t adc_read_timed(mp_obj_t self_in, mp_obj_t buf_in, mp_obj_t freq_in) {
+    pyb_obj_adc_t *self = self_in;
+
+    buffer_info_t bufinfo;
+    mp_get_buffer_raise(buf_in, &bufinfo);
+
+    // Init TIM6 at the required frequency (in Hz)
+    timer_tim6_init(mp_obj_get_int(freq_in));
+
+    // Start timer
+    HAL_TIM_Base_Start(&TIM6_Handle);
+
+    // This uses the timer in polling mode to do the sampling
+    // TODO use DMA
+    for (uint i = 0; i < bufinfo.len; i++) {
+        // Wait for the timer to trigger
+        while (__HAL_TIM_GET_FLAG(&TIM6_Handle, TIM_FLAG_UPDATE) == RESET) {
+        }
+        __HAL_TIM_CLEAR_FLAG(&TIM6_Handle, TIM_FLAG_UPDATE);
+        ((byte*)bufinfo.buf)[i] = adc_read_channel(&self->handle) >> 4;
+    }
+
+    // Stop timer
+    HAL_TIM_Base_Stop(&TIM6_Handle);
+
+    return mp_obj_new_int(bufinfo.len);
+}
+
+STATIC MP_DEFINE_CONST_FUN_OBJ_3(adc_read_timed_obj, adc_read_timed);
+
 STATIC const mp_map_elem_t adc_locals_dict_table[] = {
     { MP_OBJ_NEW_QSTR(MP_QSTR_read), (mp_obj_t)&adc_read_obj},
+    { MP_OBJ_NEW_QSTR(MP_QSTR_read_timed), (mp_obj_t)&adc_read_timed_obj},
 };
 
 STATIC MP_DEFINE_CONST_DICT(adc_locals_dict, adc_locals_dict_table);