Datasheet

ADS1255
ADS1256
SBAS288K − JUNE 2003 − REVISED SEPTEMBER 2013
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37
SYSOCAL: System Offset Calibration
Description: Performs a system offset calibration. The Offset Calibration Register (OFC) is updated after this operation.
DRDY
goes high at the beginning of the calibration. It goes low after the calibration completes and settled data is ready.
Do not send additional commands after issuing this command until DRDY
goes low indicating that the calibration is
complete.
SYSGCAL: System Gain Calibration
Description: Performs a system gain calibration. The Full-Scale Calibration Register (FSC) is updated after this operation.
DRDY
goes high at the beginning of the calibration. It goes low after the calibration completes and settled data is ready.
Do not send additional commands after issuing this command until DRDY
goes low indicating that the calibration is
complete.
SYNC: Synchronize the A/D Conversion
Description: This command synchronizes the A/D conversion. To use, first shift in the command. Then shift in the
WAKEUP command. Synchronization occurs on the first CLKIN rising edge after the first SCLK used to shift in the
WAKEUP command.
DIN
SCLK
CLKIN
••• •••
••••••
1111 1100
(SYNC)
0000 0000
(WAKEUP)
Synchronization Occurs Here
Figure 36. SYNC Command Sequence
STANDBY: Standby Mode / One-Shot Mode
Description: This command puts the ADS1255/6 into a low-power Standby mode. After issuing the STANDBY command,
make sure there is no more activity on SCLK while CS
is low, as this will interrupt Standby mode. If CS is high, SCLK activity
is allowed during Standby mode. To exit Standby mode, issue the WAKEUP command. This command can also be used
to perform single conversions (see One-Shot Mode section) .
DIN
SCLK
1111 1101
(STANDBY)
Normal Mode Standby Mode Normal Mode
0000 0000
(WAKEUP)
Figure 37. STANDBY Command Sequence
WAKEUP: Complete Synchronization or Exit Standby Mode
Description: Used in conjunction with the SYNC and STANDBY commands. Two values (all zeros or all ones) are
available for this command.
RESET: Reset Registers to Default Values
Description: Returns all registers except the CLK0 and CLK1 bits in the ADCON register to their default values.
This command will also stop the Read Continuous mode: in this case, issue the RESET command after DRDY
goes low.