This guide is for those who received their boards before March 27:
An issue was discovered where the CR2032 battery in the battery holder could prevent the BMC (Baseboard Management Controller) from booting. This battery is needed for the RTC (Real Time Clock) to maintain and track time when the Turing Pi 2 board is not connected to power. This ensures the BMC has the correct time upon its next boot.
To address this, an RTC battery board has been created:
The board replaces the CR2032 battery with a CR1220 battery and additional circuitry, providing 1.5V for the RTC (a standalone 1.5V battery won't work).
While the RTC will function with this board, time accuracy may be off. To correct this, a 5.1MΩ resistor must be soldered onto the board.
Why would I need it?
Accurate timekeeping is not essential for the BMC's functionality. It will work fine regardless of the date and time.
Many devices, like Raspberry Pi Compute Modules or routers, don't have an RTC clock and either don't use precise time or synchronize it from the internet.
However, if you need or want accurate timekeeping, you'll need to solder the additional resistor, insert the RTC battery board with the CR1220 battery, and set the time.
If you, however, need this time to be correct for any reason or just want to have it correct, you need to solder the additional resistor and insert the RTC battery board with the CR1220 battery inserted and set the time.
Future firmware updates will include internet time synchronization during BMC boot, so the BMC will have the correct time without needing the RTC fix.
How to solder the resistor in?
The SMD 5.1MΩ resistor must be soldered to the 2 capacitors near the X9 crystal. The crystal is near the BMC chip, which is located in the area marked with a red rectangle:
The X9 crystal and capacitors are to the left of the BMC chip (with this board orientation):
Here are the points to solder the resistor to:
An example of a soldered resistor:
And the schematic showing what the resistor must be connected to:
If you received your Turing Pi 2 board before March 27, 2023, you can receive an RTC battery board and five resistors upon request by filling out the form. You can either solder one yourself or have someone or an electronics repair shop do it for you