KC868-A6 Digital input IRQ

[Libramale]

Can anybody help me with information relating to the ESP32 GPIO pin used to connect the IRQ (nINT) from the PCF8574 (Digital inputs 1 to 6).

I need to be able to capture very irregular (maybe 10 per minute) but short pulses (< 10mS duration) pulses without missing any.

I would hate to have to schedule I2C reads every 5mS or less to make sure nothing is missed.

I have had a look at the KC868-A4 schematic and the DI1-DI4 pins are directly GPIO connect, not through a PCF8574 GPIO extender.

[admin]

here is ESP32 pin define of KC868-A6 : https://www.kincony.com/forum/showthread.php?tid=1962
if you want use PCF8574 INT pin, you can chose one free GPIO not used, connect to PCF8574's INT pin.

[Libramale]

@Admin

Thanks for the feedback, I did see the thread linked before posting the question.

So. just to clarify: What you are saying is that the nINT pin on the PCF8574 has not been connected to any GPIO and that I will have to strap wire it to an ESP32 GPIO.

Any chance you can share a photo showing where the PCF85743 nINT pin/pad can be intercepted and where it can be connected to an unused and suitable ESP32 GPIO.
Being primarily a FW/SW guy I would prefer not to mess around unguided on a PCB.

Thanks

[admin]

there is a extend serial port on KC868-A6 board. the free GPIO is GPIO12 and GPIO13, you can use for PCF8574's INT pin.
   

[Libramale]

there is a extend serial port on KC868-A6 board. the free GPIO is GPIO12 and GPIO13, you can use for PCF8574's nINT pin.

Thanks for the response. Your suggestion raised a couple of additional questions.

Q1. Where physically on the PCB would be best and safest place to solder strap wire to U3 PCF8574P nINT (pin 13) signal?
Q2. We need to use the spare UART/serial port for communicating to an external device. Is it possible to either of the RS232 pins for an IRQ signal?
Q3. If so, which of IO16/17 would be most suitable being floating and not pulled up or down by the SP3232EEN chip?
Q4. If so, where physically on the PCB would best and safest to solder the strap wire for using IO16/17?

For best/safest PCB solder locations can you please indicate on PCB, top or bottom, with an arrow.

Thanks again

[admin]

1. Welding directly with wires. anywhere, just easy to welding is ok.
2. RS232 on board just using RXD,RXD pins with ESP32.