UM1836

Software configuration

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2

Software configuration

Configuration of the STC3115 open source driver is done using the stc3115_Battery.h file.

This file allows the battery and application parameters to be configured with the minimum

variable set.

2.1

Battery parameters configuration

An extract of the stc3115_Battery.h file where battery parameters are defined is shown

below. A detailed explanation of the terms used in this code (CAPACITY, RINT, and

OCV_OFFSET_TAB) is also available below.

/*Battery parameters define ----------------------------------------*/

#define CAPACITY 1500 /* battery nominal capacity in mAh

*/

#define RINT 200 /* Internal battery impedance in mOhms,0 if unknown*/

#define OCV_OFFSET_TAB {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}

/* OCVTAB */

The CAPACITY parameter describes the typical battery capacity in mAh.

The RINT parameter describes the internal battery impedance in mOhm. The value has to

include battery cell impedance and battery security IC impedance. If the battery is

connected to the STC3115 by long and/or small wires, the wire impedance has also to be

included in this parameter. If this parameter is unknown, it can be declared as zero. In this

case, a default value of 200 mOhms is used for the RINT.

The OCV_OFFSET_TAB is the REG_OCVTAB register described in the STC3115

datasheet. This register can be filled by using the battery open circuit voltage (OCV) curve

(see AN4324). If the OCV adjustment table is set up at 0, the OCV curve used to monitor

the battery is the default OCV programmed in the STC3115 internal registers (see

STC3115 datasheet). This default configuration is adequate to maintain a functional

system. The OCV adjustment table must not be filled with any value below -127 or above

127.