I am using the STM32H747-I Discovery Board. When I connect the CN2 power supply to the board, it turns on, and LED5 lights up green, indicating the board is powered. However, the LCD display does not turn on. I tried enabling the backlight by setting the BL_CTRL (PJ12) pin high, but it did not work.
Previously, I raised this issue, and an ST employee provided debugging steps, as follows:
Step 1: Check if the "+5V" power supply is provided correctly. Probe either C3 or C76 on the MB1248 board.
Step 2: If step 1 confirms that 5V is provided well on the MB1248, check if the LCD board (MB1166) is receiving the 5V. Probe C3, C4, or C5 on the MB1166 board.
Step 3: If step 2 confirms that 5V is supplied to the LCD board, check if the output voltage is correct. Probe C1 or C2 on the MB1166 board. You can also measure Vfb by probing R3 on the MB1166 board.
The issue is that some of these capacitors and components are located underneath the display, making it difficult to probe them.
Can you clarify:
- Does providing a 5V power supply alone ensure that the backlight turns on? Or are there additional steps (such as setting PJ12) required to enable the backlight?
- How can I check the capacitors and components located under the display? Is there an alternative debugging method or tool to verify these points without removing the display?
Best regards,
Vani
