topic Re: LPC845 IAP, page erase in LPC Microcontrollers

LPC845 IAP, page erase

rianzu — Thu, 28 Mar 2019 08:06:51 GMT

We develop a OTA upgrade feature for a LPC845 based project.

We noticed that IAP - ERASE PAGE command (59 dec) is able to erase a single 64 byte page which is extraordinarily.

Two questions arrives:

1) Is this reliable? I mean what's behind IAP in case of loss of power during write page ?

The concern is that entire sector (where the page is) can be corrupted?

Or just page in discussion.

2) There is a restriction to not access FLASH while this IAP is in progress.

So the best approach (reliable) is to wait for IAP complete.

How can we calculate worst case wait over temp range and Vdd?

Thanks for clarifications.

Re: LPC845 IAP, page erase

Alice_Yang — Fri, 29 Mar 2019 04:09:50 GMT

Hello Rian Malcovich ,

1) " entire sector (where the page is) can be corrupted?"

-> No, only erase the page. There is "Flash_IAP" demo under LPC845 Code Bundule :

LPC84x 30MHz|Arm® Cortex®-M0+|32-bit Microcontrollers (MCUs) | NXP

I did some change to test based on this demo, confirmed page erase function:

After erase page:

then writhe this page:

2) Before access FLASH , please disable all interrupts.

About "How can we calculate worst case wait over temp range and Vdd?", sorry I'm not very clear your meaning,

could you please description it in detail.

Have a great day,
TIC

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Re: LPC845 IAP, page erase

rianzu — Mon, 01 Apr 2019 13:19:47 GMT

Understood for 1) and thank you.

For 2) the flash must NOT be accessed until IAP execution finished.

So we must have a blocking loop to allow time to elapse.

The question is how long to wait, how to calculate to have a safety margin under worst case conditions.

Re: LPC845 IAP, page erase

Alice_Yang — Tue, 02 Apr 2019 02:49:33 GMT

Hello Rian,

The IAP commands all have return Status,

we can check the Statue code to confirm whether finished:

Have a great day,
TIC

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