[WP8548] RTC charger settings

Hello,

We are working on Airprime module WP8548, with a RTC coin cell of 3V, flashed with release 12.2.
We absolutely need to set custom parameters in RTC charger.

In the datasheet rev12, on page 65 note b and c, it is said that the RTC charger voltage is programmable 2.5 / 3.0 / 3.1 / 3.2 V and also resistor setting can be 800 / 1200 / 1700 / 2100

In AT Command Reference rev 2 , page 141, it is said that “[Charging voltage] can be configured using AT!MVCOIN” but this AT command is not detailed anywhere else in the document and we didn’t succeed to use it.

QUESTIONS ARE :

  1. what are the default values of RTC charger ?
  2. can you provide detailed description of the AT commands to change these parameters ?

Thank you.

Hi,
Default value for RTC charger is 3,0(2.5V,2.1Kohm).

AT!MVCOIN : sets or queries the Coin cell configuration.The command specifies the voltage of the coin cell as well as the series resistance of the resistor in use.
The setting is persistent across power cycles.

Command Syntax: AT!MVCOIN=voltage,resistance
Query Syntax: AT!MVCOIN?
Response Syntax: !MVCOIN: voltage,resistance

0-3 0 - 3.0V
1 - 3.1V
2 - 3.2V
3 - 2.5V

0-3 0 - 2100 OHMS
1 - 1700 OHMS
2 - 1200 OHMS
3 - 800 OHMS.

Regards,
Moderator