LPC4370 performance with external SPIFI flash

[vitaliylivnov]

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)?

[ZhangJennie · Accepted solution]

HI

SPIFI is high speed interface comparing other flash interface such as high-cost parallel norflash. But the code is executed from external memory which speed is slower than on chip memory, It's normal. SPIFI flash is not designed for peak code-operation speed, but if the part of code don't care about the speed so much. SPIFI is a good choice.

Here is some testing result of SPIFI, FYI

Have a great day,
Jun Zhang

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[vitaliylivnov]

Hi, ZhangJennie 

Thank you for your answer.

Can we use a faster SPIFI chip and increase the speed of the SPI interface LPC4370 (for example, up to 102 MHz)?

And could you explain the meaning of the Score and Coremark parameters in your table?

[ZhangJennie]

Hi Vitaliy Livnov,

I don't think SPIFI can get to speed of 102M/s.

according to the latest LPC4370 datasheet, the maximal speed is 52MB/s:

Regarding to "Score and Coremark", this information is extracted from my old backup. The original author is no longer here. I don't know how they tested it.

We can understand higher "Score and Coremark"  marks means higher SPIFI performance.

Have a great day,
Jun Zhang

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[vitaliylivnov]

Thank you!

[ZhangJennie]

You are welcome!