On 2016-03-09 11:23, Maarten Brock wrote:
Hi Maarten
I think you are missing the required 1kohm resistor on your irq line :-)
/Sean
Hello Sean,
You're right, I don't have 1k. Instead I have the weak internal pull up of the
raspberry pi enabled, which gives ~50k. If 1k should solve it, then 50k should
give me max ~50 spurious interrupts. Instead I see 150.000.
And according to this page
http://www.mosaic-industries.com/embedded-systems/microcontroller-projects/raspberry-pi/gpio-pin-electrical-specifications#tab1
the raspberry pi input should even have hysteresis which means a slow rising
signal should not generate bounce-like behavior. I can only hope the hysteresis
is enabled when the pin is configured for interrupt.
I am not convinced this is the problem.
Maarten
Hi
50k is not enough pullup for the chip :-)
Take a look in www.nxp.com/documents/data_sheet/SC16IS740_750_760.pdf
It looks like you only see noise on the irq pin, are you sure you are
selecting the correct pin in your dtb?
/Sean
--
To unsubscribe from this list: send the line "unsubscribe linux-serial" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
