Monitor backup battery (VBAT) using LVD

Question

Hi, I want to monitor the backup battery voltage (VBAT) on an RA6M5 with FSP-5.1. I added the LVD stack to the project but I see BSP_FEATURE_LVD_HAS_EXT_MONITOR is disabled everywhere. 1. How can I enable it? 2. Also, should I select Monitor Number 1 or 2? 
 regards Johann

AZ [Renesas] · Accepted Answer

Yes, this is the idea. The following graphs may explain it better:

Also make sure the VBATT is within the allowable range:

AZ [Renesas] · Answer

Hello, 
 The LVD module can only monitor the VCC pin - not VBATT pin.

The battery backup function should be used after the voltage monitor 0 reset is enabled (OFS1.LVDAS bit is 0). Voltage monitor 0 level should be higher than VBATT switch level. 
 The LVD module only supports configuring voltage monitor 1 and voltage monitor 2. Voltage monitor 0 can be configured by setting the appropriate bits in the OFS1 register. This means that voltage monitor 0 settings cannot be changed at runtime.

Regards

Monitor backup battery (VBAT) using LVD

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