M-Labs/thermostat
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Fix wrong current limit duty cycle calculation

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- prev commit assumed setting 3.3V -> 3A current limit which is wrong
- Please refer to the MAX1968 datasheet for the duty cycle
calculation equation
This commit is contained in:
linuswck 2024-09-19 17:39:05 +08:00 committed by sb10q
parent b336c4f993
commit ad54842c43
1 changed files with 11 additions and 9 deletions
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20
src/channels.rs
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@ -45,7 +45,11 @@ pub const MAX_TEC_V: ElectricPotential = ElectricPotential {
units: PhantomData, units: PhantomData,
value: 4.0, value: 4.0,
}; };
const MAX_TEC_I_DUTY_TO_CURRENT_RATE: ElectricCurrent = ElectricCurrent {
dimension: PhantomData,
units: PhantomData,
value: 1.0 / (10.0 * R_SENSE / 3.3),
};
// DAC chip outputs 0-5v, which is then passed through a resistor dividor to provide 0-3v range // DAC chip outputs 0-5v, which is then passed through a resistor dividor to provide 0-3v range
const DAC_OUT_V_MAX: ElectricPotential = ElectricPotential { const DAC_OUT_V_MAX: ElectricPotential = ElectricPotential {
dimension: PhantomData, dimension: PhantomData,
@ -382,15 +386,13 @@ impl Channels {
} }
pub fn get_max_i_pos(&mut self, channel: usize) -> (ElectricCurrent, ElectricCurrent) { pub fn get_max_i_pos(&mut self, channel: usize) -> (ElectricCurrent, ElectricCurrent) {
let max = ElectricCurrent::new::<ampere>(3.0);
let duty = self.get_pwm(channel, PwmPin::MaxIPos); let duty = self.get_pwm(channel, PwmPin::MaxIPos);
(duty * max, MAX_TEC_I) (duty * MAX_TEC_I_DUTY_TO_CURRENT_RATE, MAX_TEC_I)
} }
pub fn get_max_i_neg(&mut self, channel: usize) -> (ElectricCurrent, ElectricCurrent) { pub fn get_max_i_neg(&mut self, channel: usize) -> (ElectricCurrent, ElectricCurrent) {
let max = ElectricCurrent::new::<ampere>(3.0);
let duty = self.get_pwm(channel, PwmPin::MaxINeg); let duty = self.get_pwm(channel, PwmPin::MaxINeg);
(duty * max, MAX_TEC_I) (duty * MAX_TEC_I_DUTY_TO_CURRENT_RATE, MAX_TEC_I)
} }
// Get current passing through TEC // Get current passing through TEC
@ -439,16 +441,16 @@ impl Channels {
pub fn set_max_i_pos(&mut self, channel: usize, max_i_pos: ElectricCurrent) -> (ElectricCurrent, ElectricCurrent) { pub fn set_max_i_pos(&mut self, channel: usize, max_i_pos: ElectricCurrent) -> (ElectricCurrent, ElectricCurrent) {
let max = ElectricCurrent::new::<ampere>(3.0); let max = ElectricCurrent::new::<ampere>(3.0);
let duty = (max_i_pos.min(MAX_TEC_I).max(ElectricCurrent::zero()) / max).get::<ratio>(); let duty = (max_i_pos.min(MAX_TEC_I).max(ElectricCurrent::zero()) / MAX_TEC_I_DUTY_TO_CURRENT_RATE).get::<ratio>();
let duty = self.set_pwm(channel, PwmPin::MaxIPos, duty); let duty = self.set_pwm(channel, PwmPin::MaxIPos, duty);
(duty * max, max) (duty * MAX_TEC_I_DUTY_TO_CURRENT_RATE, max)
} }
pub fn set_max_i_neg(&mut self, channel: usize, max_i_neg: ElectricCurrent) -> (ElectricCurrent, ElectricCurrent) { pub fn set_max_i_neg(&mut self, channel: usize, max_i_neg: ElectricCurrent) -> (ElectricCurrent, ElectricCurrent) {
let max = ElectricCurrent::new::<ampere>(3.0); let max = ElectricCurrent::new::<ampere>(3.0);
let duty = (max_i_neg.min(MAX_TEC_I).max(ElectricCurrent::zero()) / max).get::<ratio>(); let duty = (max_i_neg.min(MAX_TEC_I).max(ElectricCurrent::zero()) / MAX_TEC_I_DUTY_TO_CURRENT_RATE).get::<ratio>();
let duty = self.set_pwm(channel, PwmPin::MaxINeg, duty); let duty = self.set_pwm(channel, PwmPin::MaxINeg, duty);
(duty * max, max) (duty * MAX_TEC_I_DUTY_TO_CURRENT_RATE, max)
} }
fn report(&mut self, channel: usize) -> Report { fn report(&mut self, channel: usize) -> Report {