topic Re: LPC55S0 flash re-programming using reset pin vs power cycling in LPC Microcontrollers

LPC55S0 flash re-programming using reset pin vs power cycling

Ash17 — Wed, 21 Feb 2024 17:36:22 GMT

When reprogramming the LPC55S06JHI48, with the example "hello world" FW found in the SDK, we noticed that the "hello world" text does not appear in a terminal or console when we power cycle after programming. But the "hello world" text shows up if we program and then press reset. However, we discovered that the re-program does work during power cycle when we tried another FW file but for some reason resetting and power cycling makes the MCU behave differently.

Does the MCU bootloader do different tasks after a power cycle vs a reset? Is it ok to only power cycle after re-flashing (no reset)?

Re: LPC55S0 flash re-programming using reset pin vs power cycling

Alice_Yang — Thu, 22 Feb 2024 07:04:16 GMT

Hello @Ash17

About the reset difference, please refer to Table 164. Resets of UM11424.

https://www.nxp.com.cn/docs/en/user-guide/UM11424.pdf

Below just part of them:

Alice

Re: LPC55S0 flash re-programming using reset pin vs power cycling

Ash17 — Tue, 27 Feb 2024 13:51:50 GMT

Thanks! That answers my question.

Re: LPC55S0 flash re-programming using reset pin vs power cycling

Ash17 — Tue, 27 Feb 2024 14:01:03 GMT

I do want to point out that it appears that this MCU appears to have some delay during bootup where code in the flash won't properly execute until the booting is complete. Since the the RTC and MCU clock is still active during a reset but obviously not during a power-cycle, it explains why the "hello world" text shows up after reset but not after power cycle.