Change fan to use pure pwm (#2267)

* set cuatro fan settings

* set cuatro to use pure pwm

* use pwm on all boards

* remove fan max rpm configs, use pure pwm

* add comment about cooldown

* change max rpm in python side

* remove reference to max_fan_pwm in fan.h

* fully refactor fan configs into "has_fan"

* increase limits on fan test to 15% either way

* only tres for now

* doesn't matter

* not relevant anymore

---------

Co-authored-by: Adeeb Shihadeh <adeebshihadeh@gmail.com>

board/boards/board_declarations.h

@@ -29,10 +29,9 @@ struct board {
   const uint8_t led_pin[3];
   const uint8_t led_pwm_channels[3]; // leave at 0 to disable PWM
   const bool has_spi;
-  const uint16_t fan_max_rpm;
+  const bool has_fan;
   const uint16_t avdd_mV;
   const uint8_t fan_enable_cooldown_time;
-  const uint8_t fan_max_pwm;
   board_init init;
   board_init_bootloader init_bootloader;
   board_enable_can_transceiver enable_can_transceiver;

board/boards/cuatro.h

@@ -132,8 +132,7 @@ static harness_configuration cuatro_harness_config = {
 board board_cuatro = {
   .harness_config = &cuatro_harness_config,
   .has_spi = true,
-  .fan_max_rpm = 12500U,
-  .fan_max_pwm = 99U, // it can go up to 14k RPM, but 99% -> 100% is very non-linear
+  .has_fan = true,
   .avdd_mV = 1800U,
   .fan_enable_cooldown_time = 3U,
   .init = cuatro_init,

board/boards/red.h

@@ -115,8 +115,7 @@ board board_red = {
   .set_bootkick = unused_set_bootkick,
   .harness_config = &red_harness_config,
   .has_spi = false,
-  .fan_max_rpm = 0U,
-  .fan_max_pwm = 100U,
+  .has_fan = false,
   .avdd_mV = 3300U,
   .fan_enable_cooldown_time = 0U,
   .init = red_init,

board/boards/tres.h

@@ -155,8 +155,7 @@ static harness_configuration tres_harness_config = {
 board board_tres = {
   .harness_config = &tres_harness_config,
   .has_spi = true,
-  .fan_max_rpm = 6600U,
-  .fan_max_pwm = 100U,
+  .has_fan = true,
   .avdd_mV = 1800U,
   .fan_enable_cooldown_time = 3U,
   .init = tres_init,

board/drivers/fan.h

@@ -5,10 +5,13 @@ struct fan_state_t fan_state;
 static const uint8_t FAN_TICK_FREQ = 8U;
 
 void fan_set_power(uint8_t percentage) {
-  fan_state.target_rpm = ((current_board->fan_max_rpm * CLAMP(percentage, 0U, 100U)) / 100U);
+  if (percentage > 0U) {
+    fan_state.power = CLAMP(percentage, 20U, 100U);
+  } else {
+    fan_state.power = 0U;
+  }
 }
 
-void llfan_init(void);
 void fan_init(void) {
   fan_state.cooldown_counter = current_board->fan_enable_cooldown_time * FAN_TICK_FREQ;
   llfan_init();
@@ -16,9 +19,7 @@ void fan_init(void) {
 
 // Call this at FAN_TICK_FREQ
 void fan_tick(void) {
-  const float FAN_I = 6.5f;
-
-  if (current_board->fan_max_rpm > 0U) {
+  if (current_board->has_fan) {
     // Measure fan RPM
     uint16_t fan_rpm_fast = fan_state.tach_counter * (60U * FAN_TICK_FREQ / 4U);   // 4 interrupts per rotation
     fan_state.tach_counter = 0U;
@@ -31,8 +32,8 @@ void fan_tick(void) {
       print("\n");
     #endif
 
-    // Cooldown counter
-    if (fan_state.target_rpm > 0U) {
+    // Cooldown counter to prevent noise on tachometer line.
+    if (fan_state.power > 0U) {
       fan_state.cooldown_counter = current_board->fan_enable_cooldown_time * FAN_TICK_FREQ;
     } else {
       if (fan_state.cooldown_counter > 0U) {
@@ -40,18 +41,8 @@ void fan_tick(void) {
       }
     }
 
-    // Update controller
-    if (fan_state.target_rpm == 0U) {
-      fan_state.error_integral = 0.0f;
-    } else {
-      float error = (fan_state.target_rpm - fan_rpm_fast) / ((float) current_board->fan_max_rpm);
-      fan_state.error_integral += FAN_I * error;
-    }
-    fan_state.error_integral = CLAMP(fan_state.error_integral, 0U, current_board->fan_max_pwm);
-    fan_state.power = fan_state.error_integral;
-
     // Set PWM and enable line
     pwm_set(TIM3, 3, fan_state.power);
-    current_board->set_fan_enabled((fan_state.target_rpm > 0U) || (fan_state.cooldown_counter > 0U));
+    current_board->set_fan_enabled((fan_state.power > 0U) || (fan_state.cooldown_counter > 0U));
   }
 }

board/drivers/fan_declarations.h

@@ -3,7 +3,6 @@
 struct fan_state_t {
   uint16_t tach_counter;
   uint16_t rpm;
-  uint16_t target_rpm;
   uint8_t power;
   float error_integral;
   uint8_t cooldown_counter;

board/main.c

@@ -294,7 +294,7 @@ int main(void) {
   microsecond_timer_init();
 
   current_board->set_siren(false);
-  if (current_board->fan_max_rpm > 0U) {
+  if (current_board->has_fan) {
     fan_init();
   }
 

python/__init__.py

@@ -131,7 +131,7 @@ class Panda:
 
   MAX_FAN_RPMs = {
     HW_TYPE_TRES: 6600,
-    HW_TYPE_CUATRO: 12500,
+    HW_TYPE_CUATRO: 5000,
   }
 
   HARNESS_STATUS_NC = 0

tests/hitl/7_internal.py

@@ -4,18 +4,21 @@ import pytest
 from panda import Panda
 
 pytestmark = [
-  pytest.mark.test_panda_types(Panda.INTERNAL_DEVICES)
+  # TODO: re-enable this once we update the HITL devices
+  #pytest.mark.test_panda_types(Panda.INTERNAL_DEVICES)
+  pytest.mark.test_panda_types([Panda.HW_TYPE_TRES])
 ]
 
 @pytest.mark.timeout(2*60)
-def test_fan_controller(p):
+def test_fan_curve(p):
+  # ensure fan curve is (roughly) linear
+
   for power in (30, 50, 80, 100):
     p.set_fan_power(0)
     while p.get_fan_rpm() > 0:
       time.sleep(0.1)
 
-    # wait until fan spins up (and recovers if needed),
-    # then wait a bit more for the RPM to converge
+    # wait until fan spins up, then wait a bit more for the RPM to converge
     p.set_fan_power(power)
     for _ in range(20):
       time.sleep(1)
@@ -24,7 +27,7 @@ def test_fan_controller(p):
     time.sleep(5)
 
     expected_rpm = Panda.MAX_FAN_RPMs[bytes(p.get_type())] * power / 100
-    assert 0.9 * expected_rpm <= p.get_fan_rpm() <= 1.1 * expected_rpm
+    assert 0.75 * expected_rpm <= p.get_fan_rpm() <= 1.25 * expected_rpm
 
 def test_fan_cooldown(p):
   # if the fan cooldown doesn't work, we get high frequency noise on the tach line
@@ -35,21 +38,3 @@ def test_fan_cooldown(p):
   for _ in range(5):
     assert p.get_fan_rpm() <= Panda.MAX_FAN_RPMs[bytes(p.get_type())]
     time.sleep(0.5)
-
-def test_fan_overshoot(p):
-
-  # make sure it's stopped completely
-  p.set_fan_power(0)
-  while p.get_fan_rpm() > 0:
-    time.sleep(0.1)
-
-  # set it to 30% power to mimic going onroad
-  p.set_fan_power(30)
-  max_rpm = 0
-  for _ in range(50):
-    max_rpm = max(max_rpm, p.get_fan_rpm())
-    time.sleep(0.1)
-
-  # tolerate 10% overshoot
-  expected_rpm = Panda.MAX_FAN_RPMs[bytes(p.get_type())] * 30 / 100
-  assert max_rpm <= 1.1 * expected_rpm, f"Fan overshoot: {(max_rpm / expected_rpm * 100) - 100:.1f}%"