User`s guide
62
Operation Theory
4.5.3 System Synchronization Interface
SSI (System Synchronization Interface) provides the DAQ timing syn-
chronization between multiple cards. In the DAQ-2213/2214, we designed
a bi-directional SSI I/O to provide flexible connection between cards and
allow one SSI master to output the signal and up to three slaves to receive
the SSI signal. Note that the SSI signals are designed for card synchro-
nization only, not for external devices.
SSI timing signal Functionality
SSI_TIMEBASE
SSI master: send the TIMEBASE out
SSI slave: accept the SSI_TIMEBASE to replace the internal
TIMEBASE signal.
SSI_ADCONV
SSI master: send the ADCONV out
SSI slave: accept the SSI_ADCONV to replace the internal
ADCONV signal.
SSI_SCAN_START
SSI master: send the SCAN_START out
SSI slave: accept the SSI_SCAN_START to replace the
internal SCAN_START signal.
SSI_AD_TRIG
SSI master: send the internal AD_TRIG out
SSI slave: accept the SSI_AD_TRIG as the digital trigger
signal.
SSI_DA_TRIG
(for DAQ-2214)
SSI master: send the DA_TRIG out.
SSI slave: accept the SSI_DA_TRIG as the digital trigger
signal.
SSI_DAWR
(for DAQ-2214)
SSI master: send the DAWR out.
SSI slave: accept the SSI_DAWR to replace the internal
DAWR signal.
Table 15: Summary of SSI timing signals and the corresponding func-
tions as the master or slave
In the PCI form factor, there is a connector on the top right corner of the
card for the SSI. Refer to section 2.3 for the connector position. All the SSI
signals are routed to the 20-pin connector from the FPGA. To synchronize
multiple cards, users can connect a special ribbon cable (ACL-SSI) to all
the cards in a daisy-chain configuration
The 4(DAQ-2213)/6(DAQ-2214) internal timing signals could be routed to
the SSI bus through software drivers. Please refer to section 4.6.1 for
detailed information of the 4 internal timing signals. Physically the signal
routings are accomplished in the FPGA. Cards that are connected together
through the SSI bus will still achieve synchronization on the 4 timing sig-
nals.