DNA/DNR-IRIG-650 IRIG Timing Layer
Chapter 3
31
Programming with the Low Level API
Tel: 508-921-4600
www.ueidaq.com
Vers:
4.6
Date: March 2019
DNx-IRIG-650 Chap3x.fm
© Copyright 2019
United Electronic Industries, Inc.
3.2.4
Assigning TTL
outputs
The IRIG-650 board has four TTL-level output lines which can be assigned to
variety of digital signals available inside the card.
mode = CT650_OUT_TTLEN1;
ret = (hd, devn,
mode,
// mode of operation
0,
// output configuration
CT650_OUT_CFG_SRC_1PPS,
// TTL0
CT650_OUT_CFG_SRC_NRZ,
// TTL1
CT650_OUT_CFG_SRC_1PPM,
// TTL2
CT650_OUT_CFG_SRC_1PPH);
// TTL3
There are certain important flags to use for the mode of operation:
To shorten pulse duration to 40ns (the default is 60µs, shorter pulses need to be
used for any signal with output frequency in excess of 5kHz), set by these flags:
CT650_OUT_TTL3_40nS
CT650_OUT_TTL2_40nS
CT650_OUT_TTL1_40nS
CT650_OUT_TTL0_40nS
CT650_OUT_TTL_40nS
50 Ohm termination is available on three input lines, set by these flags:
CT650_OUT_RF1TERM
- Enable 50
Ω
termination for TTL RF1 (TRIGIN) input
CT650_OUT_RF0TERM
- Enable 50
Ω
termination for TTL RF0 (CLKIN) input
CT650_OUT_AMTERM
- Enable 50
Ω
termination for the AM input
One or two buffers should be enabled to drive TTL output lines (TTL0 to TTL3):
CT650_OUT_TTLEN1
- Enable buffer 1 (applies to all lines)
CT650_OUT_TTLEN0
- Enable buffer 0 (applies to all lines)
Each of the four programmable TTL outputs can be programmed to be driven by
one of the following 32 available sources:
CT650_OUT_CFG_AM_NRZ
- IRIG-AM-IN -> NRZ-L/DCLS output (debug)
CT650_OUT_CFG_GPS_FIXV
- GPS Fix_Valid output
CT650_OUT_CFG_GPS_ANSH
- GPS Antenna Shorted output
CT650_OUT_CFG_GPS_ANOK
- GPS Antenna Ok output
CT650_OUT_CFG_GPS_TXD1
- GPS TXD1 (COM1) output
CT650_OUT_CFG_GPS_TXD0
- GPS TXD0 (COM0) output
CT650_OUT_CFG_SRC_1US
- 0.000001sec pulse
CT650_OUT_CFG_MII_NRZ
- Manchester II -> NRZ sequence (reserved)
CT650_OUT_CFG_EVENT3
- Event 3 (on event: 60µs or 1ms pulse)
CT650_OUT_CFG_EVENT2
- Event 2
CT650_OUT_CFG_EVENT1
- Event 1
CT650_OUT_CFG_EVENT0
- Event 0