Hi everyone,
I started a project a few weeks ago, which for reasons of urgency I had to use a black pill board as an initial prototype, using STM32F401CCU6 (of uncertain origin). The project continued to develop almost completely until we assembled the official board with all the circuits and peripherals.
When we programmed the firmware on the new board, after some time debugging and evaluating the operation, we noticed that without the backup battery the system took about five seconds longer than the old one to show the first image on the screen. The restart process here is turn the power supply off, wait some seconds (30s to 60s) and turn it on again (repeated many times with and without the battery).
The RTC is working perfectly with the battery, it keeps the date and time as expected and loose them when the battery is removed.
We reviewed all the hardware (connections, cabling, pinout, etc.) and found no difference between the new board and the initial prototype. We are using exactly the same firmware in both.
Important points on the MCU:
- BOOT_1 on the datasheet says it doesn't matter, but I connected it to ground to test (no difference).
- The pins shown in the picture are identical to the black pill board.
- The other pins are connected to the peripheral circuits (IO, ADC, TFT and communication).
Any idea why these extra 5s?
Thank you and best regards!
