Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Flip divider resistance circuit for thermistors #90

Merged
merged 8 commits into from
May 31, 2024
Merged

Flip divider resistance circuit for thermistors #90

Changes from all commits
Commits
Show all changes
8 commits
Select commit Hold shift + click to select a range
4d2c54d
updates
ryescholin May 28, 2024
08e76ba
remove sleep time
ryescholin May 29, 2024
d838f7d
fix imports
ryescholin May 29, 2024
a51b0d1
move conversion
ryescholin May 30, 2024
c155b95
chk
ryescholin May 30, 2024
e0b92dc
Fix compilation error
samderanova May 30, 2024
0068151
update -- tested
ryescholin May 31, 2024
4111dd3
remove full scale, etc
ryescholin May 31, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
9 changes: 4 additions & 5 deletions pod-operation/src/components/lim_temperature.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -12,15 +12,14 @@ const C_TO_K_CONVERSION: f32 = 273.15;
// connected to a thermistor, with the ADS1015 is measuring the node connecting
// the two (a voltage divider circuit).

const DIVIDER_RESISTANCE: f32 = 22000.0; // Ohms
const DIVIDER_RESISTANCE: f32 = 1000.0; // Ohms
const V_IN: f32 = 5.0; // Volts
const BETA: f32 = 3950.0; // Kelvins
const R_0: f32 = 10000.0; // Ohms
const ROOM_TEMP: f32 = 25.0 + C_TO_K_CONVERSION; // Kelvins

fn voltage_to_temp(voltage: i16) -> f32 {
let voltage = f32::from(voltage) / 1000.0;
let thermistor_resistance = (voltage * DIVIDER_RESISTANCE) / (V_IN - voltage);
fn voltage_to_temp(voltage: f32) -> f32 {
let thermistor_resistance = ((V_IN - voltage) * DIVIDER_RESISTANCE) / voltage;
taesungh marked this conversation as resolved.
Show resolved Hide resolved
let r_inf = R_0 * std::f32::consts::E.powf(-BETA / ROOM_TEMP);
let temp_kelvins = BETA / (thermistor_resistance / r_inf).ln();
temp_kelvins - C_TO_K_CONVERSION
Expand All @@ -43,7 +42,7 @@ impl LimTemperature {

pub fn read_lim_temps(&mut self) -> (f32, f32, f32, f32) {
[SingleA0, SingleA1, SingleA2, SingleA3]
.map(|channel| block!(self.ads1015.read(channel)).unwrap())
.map(|channel| f32::from(block!(self.ads1015.read(channel)).unwrap()) / 1000.0)
.map(voltage_to_temp)
.into()
}
Expand Down