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heater-arm.c: respect configured PWM frequencies. 

Especially at high frequencies the achieved one is only close,
but that's entirely sufficient for our purposes.

Test: the PWM frequency on the scope should be similar to the
one configures in the board file with DEFINE_HEATER().
This commit is contained in:
Markus Hitter 2015-08-09 17:10:53 +02:00
parent 857fef578b
commit 10310e9d19
2 changed files with 22 additions and 10 deletions
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21
config/board.gen7-arm.h
View File

@ -211,17 +211,26 @@ DEFINE_TEMP_SENSOR(extruder, TT_THERMISTOR, PIO1_0,THERMISTOR_EXTRUDER)
device has the index 0 (zero).
Set 'pwm' to ...
1 for using PWM on a PWM-able pin and on/off on other pins.
0 for using on/off on a PWM-able pin, too.
frequency in Hertz (Hz) on ARM based controllers to set PWM frequency of
this pin's output. Frequency isn't always accurate, Teacup
will choose the closest possible one. FAST_PWM is ignored
on such controllers. Valid range is 2 to 200'000 Hz.
1 on AVR based controllers for using Pulse Width Modulation (PWM)
on a pin supporting it. PWM frequency can be influenced only
somewhat and only globally with FAST_PWM.
0 for using a PWM-able pin in on/off mode.
Using PWM usually gives smoother temperature control but can conflict
with slow switches, like solid state relays. PWM frequency can be
influenced globally with FAST_PWM, see below.
with slow switches, like solid state relays. A too high frequency can
overheat MOSFETs; a too low frequency can make your heater to emit audible
noise; so choose wisely.
Pins which don't allow PWM are always operated in on/off mode.
*/
//DEFINE_HEATERS_START
// name port pwm
DEFINE_HEATER(extruder, PIO0_10, 1)
//DEFINE_HEATER(bed, PIO0_11, 1)
DEFINE_HEATER(extruder, PIO0_10, 20000)
//DEFINE_HEATER(bed, PIO0_11, 10)
#define HEATER_EXTRUDER HEATER_extruder
//#define HEATER_BED HEATER_bed

11
heater-arm.c
View File

@ -115,6 +115,7 @@ void heater_init() {
PIO1_9 CT16B1_MAT0 0x1 ---
*/
if (NUM_HEATERS) { // At least one channel in use.
uint32_t freq;
// Auto-generate pin setup.
#undef DEFINE_HEATER
@ -132,10 +133,12 @@ void heater_init() {
LPC_IOCON->pin ## _CMSIS = pin ## _PWM; /* Connect to timer. */ \
/*pin ## _TIMER->IR = 0; ( = reset value) No interrupts. */ \
pin ## _TIMER->TCR = (1 << 0); /* Enable counter. */ \
/* TODO: set PWM frequency here according to configuration. */ \
/* TODO: check wether configured freq. is within range (1..65536). */ \
pin ## _TIMER->PR = /* Prescaler to */ \
F_CPU / PWM_SCALE / 1000 - 1; /* 1000 Hz. */ \
freq = F_CPU / PWM_SCALE / pwm; /* Figure PWM freq. */ \
if (freq > 65535) \
freq = 65535; \
if (freq < 1) \
freq = 1; \
pin ## _TIMER->PR = freq - 1; /* Prescaler to freq. */ \
pin ## _TIMER->MCR = (1 << 10); /* Reset on Match 3. */ \
/* PWM_SCALE - 1, so match = 255 is full off. */ \
pin ## _TIMER->MR[3] = PWM_SCALE - 1; /* Match 3 at 254. */ \