on 3217 using PC0 .. PC4

[shpi]

Tried the library on a 3217 and just get 0x00 reading (but no pointer issue) ?

[shpi]

Ok it works, but only with Arduino.h

[MX682X]

I was hoping to get it to work without the Arduino.h.
Can you post your code? And in which file was the Arduino.h missing?

[shpi]

I want to run your library complete without the Arduino crap, but it doesnt compile. Of course unmodified it works. But just with "#include <avr/interrupt.h>" it doesnt compile.

I have 4 nodes with one Y and tried to code a slider. But it seems the value, regardless it can securely detect a touch, jump around after touches and are not stabilized in 512 range?

[MX682X]

Can you copy the error message on a failed compilation? In order to make it work, I need to know what is throwing the errors.

I don't think I will be able to help with the sliders though, as I don't have a way to test it (no slider PCB).

I can tell you however, that using self-capacitance on a slider is a bad idea, there will be too much noise. An X Line is highly recommended (See Mutual Example). If you cannot spare another Pin, consider driving the other nodes as shields (see corresponding Example).

[shpi]

I use mutual capacitance :)

ptc_add_mutualcap_node(&nodes[0], PIN_TO_PTC(PIN_PC1), PIN_TO_PTC(PIN_PC0));
ptc_add_mutualcap_node(&nodes[1], PIN_TO_PTC(PIN_PC2), PIN_TO_PTC(PIN_PC0));
ptc_add_mutualcap_node(&nodes[2], PIN_TO_PTC(PIN_PC3), PIN_TO_PTC(PIN_PC0));
ptc_add_mutualcap_node(&nodes[3], PIN_TO_PTC(PIN_PC4), PIN_TO_PTC(PIN_PC0));

But the calibration varies between nodes? I cannot get one node to 512, it idles at 590. And if i touch them they change their value only +- 20 ?

[MX682X]

How do you read out the values of the nodes?
The variation of the calibration is absolutely normal. The calibration value is the reference capacitance(!) used internally for normal operation. as the pins are bonded differently (see picture as an example below) and the layout on the silicon is different too, so they will have different stray capacitances.

There are two calibration options by the way: 1 by capacitance. 2. by a reference. the function "ptc_get_node_delta(cap_sensor_t* node)" is the one you need to get the touch value minus reference.

[shpi]

Ok thanks, i just do this now in the TWI ISR:

switch (commandbyte) {

            case 0x00: TWI0.SDATA = buffer_address; break;
            case 0x01: TWI0.SDATA = sensorValue; break;
            case 0x02: TWI0.SDATA = lastButtonState;  break;
            case 0x03: TWI0.SDATA = buffer_address == 1 ? ((nodes[0].sensorData - nodes[0].reference) >> 8 ) & 0xFF : (nodes[0].sensorData - nodes[0].reference) & 0xFF; break;
            case 0x04: TWI0.SDATA = buffer_address == 1 ? ((nodes[1].sensorData - nodes[1].reference) >> 8 ) & 0xFF : (nodes[1].sensorData - nodes[1].reference) & 0xFF; break;
            case 0x05: TWI0.SDATA = buffer_address == 1 ? ((nodes[2].sensorData - nodes[2].reference) >> 8 ) & 0xFF : (nodes[2].sensorData - nodes[2].reference) & 0xFF; break;
            case 0x06: TWI0.SDATA = buffer_address == 1 ? ((nodes[3].sensorData - nodes[3].reference) >> 8 ) & 0xFF : (nodes[3].sensorData - nodes[3].reference) & 0xFF; break;
            case 0x07: TWI0.SDATA = error; break;
            default: TWI0.SDATA = 0xAA;  // Unknown command
        } 
        buffer_address++;

The result is like this:

outer:0 center:590 right:0 left:0

So it seems one has no reference?

[MX682X]

This looks like a calibration error.
You can check by looking at node[x].state.error . It is set true if calibration failed.
or node[x].hw_compCaps / ptc_get_node_cc_fempto(cap_sensor_t* node) (the value must not be too big)

or check for this event callbacks

ptc_event_callback(PTC_CB_EVENT_ERR_CALIB_LOW, node);
ptc_event_callback(PTC_CB_EVENT_ERR_CALIB_HIGH, node);
ptc_event_callback(PTC_CB_EVENT_ERR_CALIB_TO, node);

[shpi]

Ok it tells me "Calib error, Cc too low." :( The slider is indeed quiet small

[MX682X]

consider using the shield option

ptc_add_selfcap_node(&nodes[0], PIN_TO_PTC(PIN_PC1), 
    PIN_TO_PTC(PIN_PC0) | PIN_TO_PTC(PIN_PC2) | PIN_TO_PTC(PIN_PC3)  | PIN_TO_PTC(PIN_PC4) ); 
ptc_add_selfcap_node(&nodes[0], PIN_TO_PTC(PIN_PC2), 
    PIN_TO_PTC(PIN_PC0) | PIN_TO_PTC(PIN_PC1) | PIN_TO_PTC(PIN_PC3)  | PIN_TO_PTC(PIN_PC4) ); 

etc...

[shpi]

Well we need to use mutual cap. Btw we redesigned the slider and give it a next try. Ok, adjusted. Can u verify that your analog read of pins work while ptc is suspended? Made it work without Arduino.h, we just needed to make a dummy function for the arg function.

[MX682X]

Alright, I've pushed an update to make it compile in Microchip studio at least. The Dummy functions might require Link Time Optimizations enabled (-flto).
The PTC module does not do the conversion, the ADC does. Generally, I'd recommend to use the second ADC if possible. (The DA series has a second ADC by the way, but it is reserved for the PTC)
Anyway - upon suspending the library, the ADC will not be accessed by the library, so you are free to use it for yourself,
The PTC library will reconfigure the ADC for itself upon starting a conversion cycle (after resuming)
Be careful about the interrupts though, as the PTC library relies on the Window Compare and Result Ready interrupts. If you need those, you'll need to rewrite the ISRs aswell, which I don't recommend.
On a side Note: the ptc_init_ADC0() function initializes the ADC in the same way the megaTinyCore does. You might require a custom init.

[shpi]

Well couldnt get it to work with ADC0, using ADC1 now on 3217. That works :)