Checking the processor of the electronic control unit

[ricardo]

Greetings to all! Yes, I've seen this stuff.(https://rastrecurve.com/lista.php ) Good!. That's not the question, I may have phrased it incorrectly. I recorded the signatures from this processor, and after checking them, the signal on some pins did not match the recorded one. I checked it several times and the result was the same. Perhaps this is due to the peculiarities of the processor itself. Therefore, I decided to record signals from other components of the board, bypassing the processor and flash memory. What can you advise on this issue, is it so?

Hello my friend, the SAF-C509-LM and the AM29F200BB memory have inside them the famous “charger pump” the charge pumps (a charge pump is used internally to generate higher voltages necessary for writing/recording in flash memory or EEPROM), when stimulated they start operating pulsing, or literally pumping voltages and consequently current, and this oscillation creates an instability that can even change the logic level and curve during memorization and testing. They are part of and are used in low power electronics to increase and decrease voltages for different parts of the circuit, there are examples in PWM of switched power supplies, in multiplexers, in signal transceivers like max232, and many others. So how to solve this when we have this in the circuit? We recommend that you also invert the logic by changing the GND reference from negative to positive and if this does not solve the problem, adapt a 10k resistor between the positive and negative of the board during memorization and testing and then remove it (report this in the NOTE field so you don't forget it in the project). This should stabilize the capture.