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LPC4370 performance with external SPIFI flash

Question asked by Vitaliy Livnov on Jun 14, 2019
Latest reply on Jun 19, 2019 by ZhangJennie

Hello.

We are faced with the problem of slow work of some parts of the code in LPC4370. We created a test code of 2 functions that allow you to set or reset the debug pin of the microcontroller. We have repeatedly set and reset pin and measure the set time by oscilloscope. Between one pair of these functions, we added a call to the third function ExternFunc(), which has nothing to do with the test pin and can execute any code:

DebugPointSet(1);
DebugPointSet(0);

DebugPointSet(1);
DebugPointSet(0);

ExternFunc(0, 0);
DebugPointSet(1);
DebugPointSet(0);

As you can see from the waveform, the first function call takes a lot of time (about 3 µs), the second call takes about 0.5 µs, and the third call (after the intermediate function ExternFunc()) again takes about 3 µs:

 

We suspect that this delay is caused by loading code from external SPIFI-memory, which reduces the speed of the kernel ten times. Is there any way to get around this problem and achieve maximum core speed (204 MHz)?

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