ATA6870-DK10 [APPLICATION NOTE]
9228C–AUTO–02/15
6
4.
Software Description: Monitoring of Up to 12 Battery Cells
The supplied code is documented and easy to adjust for verifying the functions of the Atmel
®
ATA6870 and start BMS
application development work.
After the board has been connected as described above the microcontroller automatically starts a cyclic measurement of
voltages, temperature, and current. LED 1 indicates these cyclic measurements. It toggles in default operation. A
continuously illuminated LED1 indicates an open clamp. See
Section 4.2 “Open Cell Check” on page 7
for more information
about open clamp detection. LED 2 indicates that for some reason the MOSFETS have been disabled. The default software
disables the FETs in case of these events:
●
Overvoltage (at least 1 cell exceeds the upper default threshold of 4.2V)
●
Undervoltage (at least 1 cell exceeds the lower default threshold of 2.5V)
●
Overcurrent (the current through the shunt exceeds the default threshold of 80mA)
●
Overheating (the temperature exceeds the upper threshold, default value is 60°C)
●
Low temperature threshold (the default threshold is -20°C)
LED 3 indicates whether the Atmel ATA6870s are turned on or not. An active LED indicates that the Atmel ATA6870s are
enabled.
The Atmel ATmega32HVB has no clock divider to provide an external slower clock than 1/2 CPU clock. Requirement of
Atmel ATA6870 is f
CLK
> 2
f
SPI
. Hence, the clock frequency of 1MHz is mandatory to provide a 500kHz clock for the ADCs
of the Atmel ATA6870 and 250kHz for SPI.
Table 4-1.
LED Functions
LED
Function
LED 1
Indicates clamp is open when permanently illuminated
Indicates cyclic measurements when blinking
LED 2
On indicates disabled MOSFETs for one of the reasons listed above
LED 3
On indicates active Atmel ATA6870
