Cirrus Logic CS5463 - Manual (Page 40)

CS5463
40 DS678F3
8. AUTO-BOOT MODE USING E
2
PROM
When the CS5463 MODE pin is asserted (logic 1), the
CS5463 auto-boot mode is enabled. In auto-boot mode,
the CS5463 downloads the required commands and
register data from an external serial E
2
PROM, allowing
the CS5463 to begin performing energy measurements.
8.1 Auto-boot Configuration
A typical auto-boot serial connection between the
CS5463 and a E
2
PROM is illustrated in Figure 17. In au-
to-boot mode, the CS5463’s CS and SCLK are config-
ured as outputs. The CS5463 asserts CS (logic 0),
provides a clock on SCLK, and sends a read command
to the E
2
PROM on SDO. The CS5463 reads the us-
er-specified commands and register data presented on
the SDI pin. The E
2
PROM’s programmed data is utilized
by the CS5463 to change the designated registers’ de-
fault values and begin registering energy.
Figure 17 also shows the external connections that
would be made to a calibrator device, such as a PC or
custom calibration board. When the metering system is
installed, the calibrator would be used to control calibra-
tion and/or to program user-specified commands and
calibration values into the E
2
PROM. The user-specified
commands/data will determine the CS5463’s exact op-
eration, when the auto-boot initialization sequence is
running. Any of the valid commands can be used.
8.2 Auto-boot Data for E
2
PROM
Below is an example code set for an auto-boot se-
quence. This code is written into the E
2
PROM by the us-
er. The serial data for such a sequence is shown below
in single-byte hexidecimal notation:
- 64 00 00 60
Write Operation Mode Register, turn high-pass
filters on.
- 44 7F C4 A9
Write value of 0x7FC4A9 to Current Gain
Register.
- 48 FF B2 53
Write value of 0xFFB253 to Voltage Gain
Register.
- 74 00 00 04
Unmask bit #2 (LSD) in the Mask Register.
- E8
Start continuous conversions
- 78 00 01 00
Write STOP bit to Control Register, to terminate
auto-boot initialization sequence.
8.3 Which E
2
PROMs Can Be Used?
Several industry-standard serial E
2
PROMs that will suc-
cessfully run auto-boot with the CS5461A are listed be-
low:
• Atmel AT25010, AT25020 or AT25040
• National Semiconductor NM25C040M8 or NM25020M8
• Xicor X25040SI
These types of serial E
2
PROMs expect a specific 8-bit
command (00000011) in order to perform a memory
read. The CS5461A has been hardware programmed to
transmit this 8-bit command to the E
2
PROM at the be-
ginning of the auto-boot sequence.
CS5463 EEPROM
EOUT1
EOUT2
MODE
SCLK
SDI
SDO
CS
SCK
SO
SI
CS
Connector to Calibrator
VD+
5 K
5 K
Mech. Counter
Stepper Motor
or
Figure 17. Typical Interface of E
2
PROM to CS5463