Datasheet

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UDG−04099

21−V pulse applied to

PROG pin for 50 ms

Host enables E2PROM

programming mode. Write data

0xDD to address 0x6E

Host writes data in addresses

0x76 − 0x7F

Host reads data

address 0x76

Write data 0x00 to

address 0x6E

Programmed

0x7F?

Host increments

address and reads

Yes

Communicating With the bq27000 (HDQ interface)

bq27000 , bq27200

SLUS556D – SEPTEMBER 2004 – REVISED MARCH 2006

Figure 6. EEPROM Programming Flow

It is not required that addresses 0x76 — 0x7F be programmed at the same time or in any particular order. The

programming method illustrated in Figure 6 can be used to program any of the bytes as long as the sequence of

Enable, Write, Read, Apply Programming Pulse, and Disable is followed.

The bq27000 includes a single-wire HDQ serial data interface. Host processors, configured for either polled or

interrupt processing, can use the interface to access various bq27000 registers. The HDQ pin is an open-drain

device, which requires an external pullup resistor. The interface uses a command-based protocol, where the host

processor sends a command byte to the bq27000. The command directs the bq27000 either to store the next

eight bits of data received to a register specified by the command byte or to output the eight bits of data from a

The communication protocol is asynchronous return-to-one and is referenced to V

. Command and data bytes

consist of a stream of eight bits that have a maximum transmission rate of 5 Kbits/s. The least-significant bit of a

command or data byte is transmitted first. Data input from the bqJUNIOR can be sampled using the pulse-width

capture timers available on some microcontrollers. A UART can also be configured to communicate with the

bq27000.

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