fix: use int64 in ReadTemperature to avoid overflow

rdon · deadprogram · commit e29e58391932 · 2025-09-19T11:30:50.000+02:00
diff --git a/src/machine/machine_rp2_adc.go b/src/machine/machine_rp2_adc.go
@@ -100,7 +100,8 @@ func ReadTemperature() (millicelsius int32) {
 	rp.ADC.CS.SetBits(rp.ADC_CS_TS_EN)
 
 	// T = 27 - (ADC_voltage - 0.706)/0.001721
-	return (27000<<16 - (int32(thermChan.getVoltage())-706<<16)*581) >> 16
+	// 1/0.001721 ≈ 581
+	return int32(((int64(27000) << 16) - ((int64(thermChan.getVoltage()) - (int64(706) << 16)) * 581)) >> 16)
 }
 
 // waitForReady spins waiting for the ADC peripheral to become ready.

Original file line number	Diff line number	Diff line change
`@@ -100,7 +100,8 @@ func ReadTemperature() (millicelsius int32) {`
`100`	`100`	`rp.ADC.CS.SetBits(rp.ADC_CS_TS_EN)`
`101`	`101`
`102`	`102`	`// T = 27 - (ADC_voltage - 0.706)/0.001721`
`103`		`- return (27000<<16 - (int32(thermChan.getVoltage())-706<<16)*581) >> 16`
	`103`	`+ // 1/0.001721 ≈ 581`
	`104`	`+ return int32(((int64(27000) << 16) - ((int64(thermChan.getVoltage()) - (int64(706) << 16)) * 581)) >> 16)`
`104`	`105`	`}`
`105`	`106`
`106`	`107`	`// waitForReady spins waiting for the ADC peripheral to become ready.`