Enabling And Disabling The Extemal Trigger; Enabling And Disabling Intemrprs; Conversion Modes/Triggering - Real Time Devices AD1200 User Manual

. Enabling and Disabling the External Trigger
Any time you use the external trigger or the pacer clock, this bit at port BA + 5 must be set high to enable A/D
conversions.
. Enabling and Disabling Interrupts
Any time you use intemrpts, ttris bit at port BA + 5 must be set high to enable the IRQ circuitry.
. Conversion Modes/Triggering
The 1200 has three riggering (conversion) modes. Figure 4-1 shows ttre timing diagram for A/D conversions.
This section describes the converSion modes.
Internal vs. External Triggering. With internal triggering (also called software triggering), conversions are
initiated by writing a value to the START COI.{VERT port at BA + 0 on the board. Wittr external triggering,
conversions are initiated by applying a high TTL signal to the extemal TRIGGER IN pin (VZ-39). Any TTL signal
can be used as a trigger source. In fact, you can use tle timer/counter outputs as a trigger source.
Trigger
End-of-Convert
(Eoc)
Data
Read
Fig. 4-1 - A/D Conversion Timing Diagram, Alt Modes
l{-
5 psec --+
|
4-r2