mirrors
/
micropython
mirror of https://github.com/micropython/micropython.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

stm32/adc: Optimise read_timed_multi() by caching buffer pointers.

This commit is contained in:
Damien George 2018-04-11 14:08:23 +10:00
parent 4f40fa5cf4
commit aebd9701a7
2 changed files with 7 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
docs/library/pyb.ADC.rst
View File

@ -125,9 +125,10 @@ Methods
The maximum rate depends on factors including the data width and the
number of ADC's being read. In testing two ADC's were sampled at a timer
rate of 140KHz without overrun. Samples were missed at 180KHz. At high
sample rates disabling interrupts for the duration can reduce the risk
of sporadic data loss.
rate of 210kHz without overrun. Samples were missed at 215kHz. For three
ADC's the limit is around 140kHz, and for four it is around 110kHz.
At high sample rates disabling interrupts for the duration can reduce the
risk of sporadic data loss.
The ADCAll Object
-----------------

6
ports/stm32/adc.c
View File

@ -475,12 +475,14 @@ STATIC mp_obj_t adc_read_timed_multi(mp_obj_t adc_array_in, mp_obj_t buf_array_i
mp_buffer_info_t bufinfo;
mp_get_buffer_raise(buf_array[0], &bufinfo, MP_BUFFER_WRITE);
size_t typesize = mp_binary_get_size('@', bufinfo.typecode, NULL);
void *bufptrs[nbufs];
for (uint array_index = 0; array_index < nbufs; array_index++) {
mp_buffer_info_t bufinfo_curr;
mp_get_buffer_raise(buf_array[array_index], &bufinfo_curr, MP_BUFFER_WRITE);
if ((bufinfo.len != bufinfo_curr.len) || (bufinfo.typecode != bufinfo_curr.typecode)) {
mp_raise_ValueError("size and type of buffers must match");
}
bufptrs[array_index] = bufinfo_curr.buf;
}
// Use the supplied timer object as the sampling time base
@ -541,9 +543,7 @@ STATIC mp_obj_t adc_read_timed_multi(mp_obj_t adc_array_in, mp_obj_t buf_array_i
if (typesize == 1) {
value >>= 4;
}
mp_buffer_info_t bufinfo_curr; // Get buf for current ADC
mp_get_buffer_raise(buf_array[array_index], &bufinfo_curr, MP_BUFFER_WRITE);
mp_binary_set_val_array_from_int(bufinfo_curr.typecode, bufinfo_curr.buf, elem_index, value);
mp_binary_set_val_array_from_int(bufinfo.typecode, bufptrs[array_index], elem_index, value);
}
}