Hi Colby etc...
Is there any thread that addresses how the reflash process actually works?
I would like to know:
1) What state is the 68HC16 in with the ignition OFF? Is it powered down, or in some sort of stdby mode, or actually executing code? (for my following questions I assume it is powered down)
2) What happens when the ignition is turned ON? Does the HC16 execute code from it's reset vector? Is this the stuff at the beginning of the image that ECUFlash reads? Or is the TPU involved somehow?
3) Presumably the flash kernel is written into RAM somehow... Is the HC16 still executing code while this is written in, or are you instructing the TPU to halt the HC16, and then vector to the kernel afterwards?
4) Which processor HC16 / TPU implements the SSM protocol?
5) Where it the TPU code stored (is this part of the image that we read / write)?
6) What is actually on the ECU board? Are there any memory mapped devices (FPGA / CPLD / ASIC ect), which could impose a H/W version compatibility issue with F/W upgrade?
One of the visualisations in my mind is that the TPU masters the HC16, and is executed from reset... Implements the SSM protocol... Verifies the HC16 code, and brings the HC16 out of reset when it determines the code is OK.
What I'm really after is to know whether I flash a newer F/W image to the ECU, and some sort of H/W compatibility issue occurs, and the ECU locks, will some other processor (TPU?) still implement the SSM protocol such that I can get back in and re-write the flash?
Heeellllppp, as this is the main issue worrying me from writing a new flash image to my ECU!