MSP430FG6626: 10us interrupt latency

r c84546

Part Number: MSP430FG6626

I am developing an applicaiton using the MSP-TS430PZ1100AUSB dev board.

I've set ACLK, SMCLK, and MCLK to XT2 (4 MHZ) and verified ACLK and SMCLK are indeed 4MHZ by measuring the clocks at the output pins.

I've wired 2 GPIO pins together, and enabled low to high interrupt on one. When I set one pin high, the interrupt handler does run but the latency is very long, 10us.

It should be around 6 cycles , or 1.5 us.

I will post code if needed, but any obvious things I should check first?

over 3 years ago

0 Dennis Lehman over 3 years ago

TI__Guru 60301 points

Hello r c84546, Sure, you can share your code. Reduce it to the smallest possible size that demonstrates the problem. How are you measuring the time?

0 r c84546 over 3 years ago in reply to Dennis Lehman

Prodigy 100 points

Thanks for the reply Dennis.

I discovered my issue, the frequency of the interrupt source was too high and the interrupt handler could not keep up which I misinterpreted as long latency.

I am setting a gpio pin high in the handler and using a scope to measure interrupt latency, is it about 10 cycles.

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MSP430FG6626: 10us interrupt latency