CS5464 datasheet(41/46 Pages) CIRRUS

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CS5464

DS682F3

10.E2PROM OPERATION

The CS5464 can accept commands from a serial

E2PROM connected to the serial interface instead of a

host microcontroller. A high level (logic 1) on the MODE

input indicates that an E2PROM is connected. This

makes the CS and SCLK pins become driven outputs.

After reset and after running the initialization program,

the CS5464 begins reading commands from the con-

nected E2PROM.

10.1 E2PROM Configuration

A typical connection between the CS5464 and a

E2PROM is shown in Figure 13.

The CS5464 asserts CS (logic 0), clocks SCLK, and

sends Read commands to the E2PROM on SDO.

Command format is identical to microcontroller mode,

except the CS5464 will not attempt to write to the EE de-

vice. The command sequence stops when the STOP bit

in the Control register (Ctrl) is written by the command

sequence.

Figure 13 also shows the external connections that

would be made to a calibration device, such as a note-

book computer, handheld calibrator, or tester during

meter assembly, The calibrator or tester can be used to

control the CS5464 during calibration and program the

required values into the E2PROM.

10.2 E2PROM Code

The EEPROM code should do the following:

1. Set any Configuration or Control register bits, such as

HPF enables and phase compensation settings.

2. Write any calibration data to gain and offset registers.

3. Set energy output pulse width, rate, and formats.

4. Execute a Continuous Conversion command.

5. Set the STOP bit in the Control register (last).

Below is an example E2PROM code set.

7E 00 00 01

Change to page 1.

60 00 01 E0

Write Modes Register, turn high-pass filters on.

42 7F C4 A9

Write value of 0x7FC4A9 to I1GAIN register.

46 FF B2 53

Write value of 0xFFB253 to V1GAIN register.

50 7F C4 A9

Write value of 0x7FC4A9 to I2GAIN register.

54 FF B2 53

Write value of 0xFFB253 to V2GAIN register.

7E 00 00 00

Change to page 0.

74 00 00 04

Set LSD bit to 1 in the Mask register.

Start continuous conversions

78 00 01 00

Write STOP bit to the Control register (Ctrl) to

terminate E2PROM command sequence.

10.3 Which E2PROMs Can Be Used?

Several industry-standard serial E2PROMs can be used

with the CS5464. Some are listed below:

•

Atmel AT25010, AT25020 or AT25040

•

National Semiconductor NM25C040M8 or NM25020M8

•

Xicor X25040SI

These serial E2PROMs expect a specific 8-bit com-

mand (00000011) in order to perform a memory read.

The CS5464 has been hardware programmed to trans-

mit this 8-bit command to the E2PROM after reset.

CS5464

EEPROM

MODE

SCLK

SDI

SDO

SCK

Connector to Calibrator

5 K

Pulse Output

Counter

Figure 13. Typical Interface of E2PROM to CS5464

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