Cirrus Logic CDB5461AU - Manual (Page 8)

CDB5461AU
8 DS661DB1
1.3 Auto-boot Mode
With a jumper connection on J18 (AUTO-BOOT ENABLE), the CS5461A operates in auto-boot mode and the
CDB5461AU board operates in a stand-alone manner without connecting to a PC. When in auto-boot mode, a hard-
ware reset (pressing on S1) will cause the CS5461A to boot up using the serial data from the serial EEPROM on
the board (U10). When the CS5461A is in auto-boot mode, the SPI connections between the microcontroller and
the CS5461A are removed and GUI software can not access the CS5461A registers and functions.
The EEPROM must be programmed prior to the auto-boot sequence. When the CDB5461AU Evaluation Board is
sent from the factory, the EEPROM is programmed with the following CS5461A command/data sequence:
– 40 00 00 61
– Set configuration Register, turn high-pass filters on, set K = 1;
– 4C 00 7D 00
– Set PulseRateE1,2 Register to 1000 Hz;
– 74 00 00 04
– Unmask bit #2 (LSD) in the Mask Register
– E8
– Start continuous conversion
– 78 00 01 00
– Write to the STOP bit in the Control Register, to terminate auto-boot sequence.
This sequence programs the CS5461A for continuous conversion mode. If voltage and current signals are applied
to the inputs, the CS5461A will issue pulses on the /E1, /E2 and /E3 pins. See the CS5460A data sheet for more
details on auto-boot.