Battery Status Monitoring - Intermec CK30 Service Manual

Chapter 4 — Theory of Operation

Battery Status Monitoring

60
Where = ACK from PXA255,
[ack]
Hex Command
0x10 SetLowBatLED
0x11 ClearLowBatLED
0x12 PSCSoftwareVer
0x30 ReadMainBatVoltage
0x40 ReadSuperCapVoltage
0x50 ReadTemperature
0x5A PSCTest
0x60 ColdBoot
0x61 WarmBoot
0x70 SuperCapChargeEnable
0x71 SuperCapChargeDisable
0x80 StartLowBatLEDFlash
0x81 StopLowBatLEDFlash
Several commands can be issued in a single burst before the host I2C
driver attempts to read return values back from the PSC.
Examples:
([W] = Write, [R] = Read, [A] = Ack, [N] = Nak)
A typical battery/supercap/temperature status request:
[Start]#12[W][A]30[A]40[A]50[A][Start]#12[R][A]30[A]95[A]
40[A]E1[A]50[A]56[N][Stop]
A warm boot command followed by a battery/supercap/temperature status
request:
[Start]#12[W][A]61[A][Start]#12[W][A]30[A]40[A]50[A]
[Start]#12[R][A]61[A]30[A]97[A]40[A]E0[A]50[N][Stop]
Main battery voltage under load is scaled through operational amplifiers
U41, sampled through the PSC A/D converter, and made available to
system power management software for accurate on-display fuel gauging
and device power management in the low-battery operating region.
Reference D14 and operational amplifiers U41 provide the reference
voltage for the PIC A/D. The PSC sends raw A/D data over the I2C bus
in response to I2C commands sent approximately every 3 seconds from the
power management software running on the PXA255 (See "PSC 12C
Syntax" on page 59).
CK30 internal temperature is sensed by thermistor RT3, read through a
PSC A/D, and sent to the OS over the I2C bus in response to I2C
command.
= NAK from PXA255
[nak]
Return Data
0x10
0x11
0x12 + PSC firmware version byte
0x30 + main battery voltage byte
0x40 + supercap voltage byte
0x50 + temperature byte
0x5A
0x60
0x61
0x70
0x71
0x80
0x81
CK30 Handheld Computer Service Manual