Calibrate CJC at next boot (#1398)

Changes Cold Junction Compensation (Tip Offset / CJC) to be performed during bootup time. (After starting in settings)

4 files changed, 56 insertions, 46 deletions

diff --git a/Documentation/DebugMenu.md b/Documentation/DebugMenu.md
index a0553a24..057f312c 100644
--- a/Documentation/DebugMenu.md
+++ b/Documentation/DebugMenu.md
@@ -3,9 +3,9 @@
 In this firmware there is extra debugging information in a hidden sub-menu.

 This menu is meant to be simple, so it has no fancy GUI animations.

 

-- Access by pressing the rear (``-/B``) button on the iron while it is on the home screen.

-- To scroll through the menu, use the front (``+/A``) button.

-- To exit, use the rear (``-/B``) button again.

+- Access it by pressing the rear button (`-/B`) on the iron while it is on the home screen.

+- Use the front button (`+/A`) to scroll through the menu.

+- To exit, use the rear button (`-/B`) again.

 

 ## Menu items

 

@@ -15,15 +15,6 @@ Items are shown in the menu on a single line, so they use short codes and appear
 - This is used by Irons that have an ID and serial number to help check if the iron is authentic. All Pinecil V1 show the same ID number as this is the number programmed into the MCU.

 - The new Pinecil V2 released Aug. 2, 2022 now uses MCU BL706, which enables generating a unique ID/Serial number to every iron. This can be used to verify your [Pinecil authenticity here](https://pinecil.pine64.org/).

 

-### Time

-

-This is just uptime; it shows how many deciseconds the unit has been powered for (600 ds = 1 minute).

-

-### Move

-

-This is the last timestamp of movement. When the iron is moved, this should update to match the Time field (previous menu item).

-This can be used for checking performance of the movement detection code.

-

 ### ACC

 

 This indicates the accelerometer that is fitted inside the unit.

@@ -33,47 +24,60 @@ This indicates the accelerometer that is fitted inside the unit.
 - BMA223

 - MSA301

 - SC7A20

-- None detected -> running in fallback without movement detection

+- None -> running in fallback without movement detection

 - Scanning -> Still searching I2C for one

 

-### Tip Res

+### PWR

 

-This indicates the tip resistance that the device is currently using. For devices with multiple possible values to choose from (Pinecil V2), the appropriate value is automatically detected at every boot-up. Tip should be installed before boot-up or reading can not be done.

+This indicates the current power source for the iron.

+This may change during power up as the sources are negotiated in turn.

+

+- **DC** input (dumb)

+- **QC** input (We used QC2/3 negotiation for current supply)

+- **PD W. VBus** input (PD subsystem is used to negotiate for current supply); and VBus is connected to your input power source

+- **PD No VBus** input (PD subsystem is used to negotiate for current supply); and VBus is **NOT** connected to your input power source. If it is Not required or possible to do a special mod of your PCB (i.e. late model V1, some early Green PCB models) then [PD No VBus] displays on-screen ([see details and PD Debug section below](/Documentation/DebugMenu.md#pd-debug-menu)).

 

-### RTip

+### Vin

 

-This is the raw tip reading in μV. Tip must be installed or reading will be high/inaccurate. At cool, the range of 700-1000 is normal for larger tips and ~1500 for smaller tips (TS80). This is used to evaluate the calibration routines.

+The input voltage as read by the internal ADC. Can be used to sanity check it is being read correctly.

 

-### CTip

+### Tip C

 

-This is the tip temperature in degrees Celsius.

+This is the tip temperature in °C.

 This can be used with RTip for assessing temperature processing performance.

 

-### CHan

+### Han C

 

-This is the handle temperature or more accurately the reading of the Cold Junction Compensation (CJC) temperature sensor. This is expressed in °C x 10 (29.0 °C ambient should read as 290). Range of 200-400 (20-40 °C) is normal depending on how hot/cold the room is and how long power has been plugged in which warms the PCB further.

+This is the handle temperature or more accurately the reading of the Cold Junction Compensation (CJC) temperature sensor. This is expressed in °C. Range of 20-40 °C is normal depending on how hot/cold the room is and how long power has been plugged in which warms the PCB further.

 This is used for CJC of the tip temperature.

  > If CHan is extremely high, this indicates the temperature sensor isn't reading correctly ([see Troubleshooting](/Documentation/Troubleshooting.md))

 

 

-### CMax

+### Max C

 

-This indicates the max temperature in °Celsius that the system estimates it can measure the tip reliably to.

+This indicates the max temperature in °C that the system estimates it can measure the tip reliably to.

 This is dependent on a few factors including the handle temperature so it can move around during use. As you use the iron, the Max increases to a point.

 

-### Vin

+### UpTime

 

-The input voltage as read by the internal ADC. Can be used to sanity check it is being read correctly.

+This shows how many deciseconds the unit has been powered for (600 ds = 1 minute).

 

-### PWR

+### Move

 

-This indicates the current power source for the iron.

-This may change during power up as the sources are negotiated in turn.

+This is the last timestamp of movement. When the iron is moved, this should update to match the Time field (previous menu item).

+This can be used for checking performance of the movement detection code.

 

-- **DC** input (dumb)

-- **QC** input (We used QC2/3 negotiation for current supply)

-- **PD W. VBus** input (PD subsystem is used to negotiate for current supply); and VBus is connected to your input power source

-- **PD No VBus** input (PD subsystem is used to negotiate for current supply); and VBus is **NOT** connected to your input power source. If it is Not required or possible to do a special mod of your PCB (i.e. late model V1, some early Green PCB models) then [PD No VBus] displays on-screen ([see details and PD Debug section below](/Documentation/DebugMenu.md#pd-debug-menu)).

+### Tip Res

+

+This indicates the tip resistance that the device is currently using. For devices with multiple possible values to choose from (Pinecil V2), the appropriate value is automatically detected at every boot-up. Tip should be installed before boot-up or reading can not be done.

+

+### Tip R

+

+This is the raw tip reading in μV. Tip must be installed or reading will be high/inaccurate. At cool, the range of 700-1000 is normal for larger tips and ~1500 for smaller tips (TS80). This is used to evaluate the calibration routines.

+

+### Tip O

+

+This is the offset resulting from the *'Cold Junction Compensation Calibration'*.

 

 ### HW G

 

diff --git a/Documentation/Menu.md b/Documentation/Menu.md
index da56b561..b073cf0c 100644
--- a/Documentation/Menu.md
+++ b/Documentation/Menu.md
@@ -44,15 +44,16 @@ What this is for: some tips have an offset on their readings which causes issues
 
 Caution: if the method below is not followed, the iron could be worse than before calibration. If you need to repeat the method, first unplug and let the handle/PCB cool down to room temperature.
 
-1. Connect power to your iron (tip should be installed).
-2. **Critical: make sure the tip & handle is at room temperature** (wait a good while after using the iron before calibration)
-3. Using (`-/B`) scroll down to Advanced settings > press (`+/A`) to select > then (`-/B`) to scroll to Calibrate temperature? > press (`+/A`)
-4. Important warning message is shown: *Confirm the tip & device are at room temperature before starting!* 
-5. Press the (`+/A`) button to confirm (tip/handle are at ambient temperature).
-6. Display shows **`....`** for a short time as the unit measures and compares the tip and handle temperatures.
-7. The display then goes back to *TMP CAL* and displays your *Offset number*. You generally don't need this offset unless debugging issues.
-8. After you see an Offset number, calibration is done, just exit the settings menu normally, use (`-/B`).
-9. You're done, enjoy your iron!
+1. Connect power to your device.
+2. Go to **`Advanced Settings`** using (`-/B`) and press (`+/A`) to select it. Use (`-/B`) to scroll to **`Calibrate CJC at next boot`** and confirm with (`+/A`).
+3. Accept the *'warning text'* with (`+/A`).
+3. Exit the settings menu as usual by pressing and holding (`-/B`).
+4. Unplug you device.
+5. **Critical: Make sure a tip is attached & wait until the tip & handle are at room temperature.** (Wait a reasonable amount of time after having used the device.)
+6. Power the device and ideally keep it out of your hands (You know it might get warm.).
+7. The display shows **`....`** for a short time while the device measures and compares the tip and handle voltages.
+8. As a result the new *Offset value* is displayed. This value can later be viewed in the **`Debug menu`**.
+9. Calibration is done and the device proceeds booting.
 
 Note: offsets are dependant on your tip, temperature sensor, and the MCU. It's the culmination of tolerances at rest. Typical values are 700-1000 range. This is only designed to be used at boot while cold (ambient room temperature), as temperatures drift apart as soon as power is connected. Doing this reading repeatedly could result in wide varience of the offset number and/or incorrect calibration.
 
diff --git a/Documentation/Settings.md b/Documentation/Settings.md
index dc8296c4..7501a2ad 100644
--- a/Documentation/Settings.md
+++ b/Documentation/Settings.md
@@ -125,13 +125,18 @@ On device help text:
 
 Flash temperature reading at idle if tip is hot
 
-### Setting: Calibrate tip CJC
+### Setting: Calibrate CJC at next boot
 
-Used to calibrate the ADC+Op-amp offsets for the tip. This calibration must be performed when the tip temperature and the handle temperature are equal. Generally not required unless your device is reading more than 5°C off target.
+Note:
+If the difference between the target temperature and the measured temperature is less than 5°C, **calibration is NOT required at all**.
+
+This is used to calibrate the offset between ADC and Op-amp of the tip at next boot (Idealy it has to be done at boot, before internal components get warm.). But this setting is ***not permanent!*** It resetes after the calibration is completed (At next boot the checkbox will be unchecked!). If you need to repeat the calibration however, you have to set the checkbox *again*, unplug your device and let it cool down to room/ambient temperature & power it up, idealy while it sits on the desk.
+
+Hence, never repeat the calibration in quick succession!
 
 On device help text:
 
-Tip-temperature Cold Junction Compensation (not needed if Tip is +/- 5°C of display)
+Calibrate tip Cold Junction Compensation at the next boot (not required if Delta T is < 5°C)
 
 ### Setting: Restore default settings
 
diff --git a/Documentation/Troubleshooting.md b/Documentation/Troubleshooting.md
index 4b4d56cf..5eacc38b 100644
--- a/Documentation/Troubleshooting.md
+++ b/Documentation/Troubleshooting.md
@@ -46,13 +46,13 @@ If `CHan` is reading low:
 - Check the power pin connection on the TMP36
 - Check pullup resistor on the NTC thermistor
 - Check no bridged pins or weak shorts on the signal to nearby pins on MCU or temperature sensor
-- Reflow/resolder the the aforementioned components
+- Reflow/resolder the aforementioned components
 
 If `CHan` is reading higher
 
 - Check ground connections on the sensors
 - Check no bridged pins or weak shorts on the signal to nearby pins on MCU or temperature sensor
-- Reflow/resolder the the aforementioned components
+- Reflow/resolder the aforementioned components
 
 ## No display OR dots on the display