BQ27000EVM Datasheet, PDF (13/19 Pages) Texas Instruments – bq27000 Single Cell Battery Fuel Gauge Evaluation Module

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Operation
8.2.3 Resetting the bq27000
The bq27000 can be reset at anytime by using the Options|Special Options|Reset bq27000 from the
pulldown menu. When reset, the bq27000 loads the configuration values from EEPROM and set the
remaining capacity registers to zero.
8.3 The Registers Screen
In the Registers screen all of bq27000's RAM registers are displayed.
8.3.1 Options Menu
This menu allows the user to select among different options. These options include whether or not to
enable scan of registers, select the file logging time rate, select the type of communication protocol (HDQ
or I2C) and select the type of communication interface (EV2300 or EV2200).
8.3.2 Commands Menu
With bq27000 there are several commands that are performed by setting the appropriate bit in the MODE
register and then writing 0xA9 into address 0x00. With the Commands menu of the EVSW the user may
perform the commands automatically. Among the selections are:
• WRTNAC - If a user desires to write the NAC register to a specific value, the user would write that
value to the AT RATE register and then select WRTNAC from the Commands menu.
• DONE - The user selects DONE when charging is complete and the monitor is not able to detect taper
current. It forces an update of internal registers to represent a full battery condition.
• PRST - This command causes a reset except that NAC, LMD and the CI bit in FLAGS register are not
restored to initial values. This command is intended for manufacturing use.
• FRST - This command will re-initialize all RAM registers. This command is intended for manufacturing
use.
• SHIP - Once this command is given the bq27000 will enter ship mode if the HDQ has been pulled low
for at least 18 seconds. A full reset is forced when the part leaves ship mode.
8.3.3 GPIO Menu
This menu selects the function of the GPIO pin as an ouptut or input. If selected as an output, the open
drain output can be set to on or off.
8.4 The EEPROM Screen
The EEPROM screen allows the user to read and write the 10 EEPROM registers of bq27000. There are
checkboxes (Enable LMD Aging, Customer ID #) that when its status are changed it will cause an
automatic write to the EEPROM to ensure that the selections apply accordingly. Always when writing to
the EEPROM ensure that the 21V pulse to PROG pin is available.
When selecting the status of Customer ID #1 (DCOMP) and Customer ID #2 (TCOMP), the DCFIX and
TCFIX bits in the Pack Configuration EEPROM register will also be written. For example, if the DCOMP is
set for discharge compensation then the DCFIX bit will be clear. If the DCOMP register is selected to be
used as Customer ID #2 then the DCFIX bit will be set.
The Taper Current EEPROM register includes the Taper Current value (bits 0-6) and the Enable Last
Measure Discharge Aging (bit 7). When registers are displayed with engineering units, the value shown for
Taper Current is just taking in consideration bits 0-6. The user must rely on the Enable LMD Aging
checkbox to determine this feature. When registers are not displayed in engineering units, the value
shown for Taper Current includes all 8 bits of this register represented in hex.
SLUU157A – September 2004 – Revised November 2004
bq27000 Single Cell Battery Fuel Gauge
13
Evaluation Module