Best MCU for the lowest input capture interrupt latency

[SiliconWizard]

[jemangedeslolos]

Hello everyone 

I received my PCB and I gave a try to a dsPIC33CK ( exact ref:dsPIC33CK128MP503 ).
There are more parameters than with dsPIC33EP so I don't know if I was doing something wrong with dsPIC33EP but I was able to make it work with this little dsPIC33CK 



The latency is not as low as other settings but at leat It works 

[NorthGuy]

The latency is not as low as other settings but at leat It works 

Congratulations!

I'm sure, on EP, there was some sort of small thing you somehow overlooked.

Roughly 60 ns (if judging by the 1/2 voltage level). I would expect it to be a little bit better. Is the CPU running at 100 MHz (200 MHz Fosc)? Have you used the dedicated INT pin (pin #19) for the signal?

Anyway, this is way faster than you would get with the interrupt.

[SpacedCowboy]

Resurrecting an old thread, but I happened to be searching for IO expanders and the results I found reminded me of this. The SX150x chips are IO expanders that embed a PLD, and you can use the I2C interface to determine what happens when an IO changes state. The max response time looks to be 25ns if you're running your VDD/VIO at 5v, going down to 125ns if you're running at 1.2v VDD/IO. 25ns is, I suspect, a reasonably good figure for anything that's not a dedicated FPGA/CPLD; probably way too late to be useful but thought it was worth mentioning...

[PCB.Wiz]

Resurrecting an old thread, but I happened to be searching for IO expanders and the results I found reminded me of this. The SX150x chips are IO expanders that embed a PLD, and you can use the I2C interface to determine what happens when an IO changes state...

Interesting parts, the Logic looks to be very simple, non registered, with maximum of 3 line to 1 line any pattern defined by a single byte bit pattern. ( ie a 3 input universal gate level )

If you were using external parts for this, the SiLego GreenPAK parts have more advanced logic capabilities
https://www.renesas.com/us/en/products/programmable-mixed-signal-asic-ip-products/greenpak-programmable-mixed-signal-products#parametric_options


They started with OTP parts, but have expanded recently to include MTP parts config over i2c