BitScope performs data capture according to a selected trace mode.
The trace mode controls how many analog channels to capture and what type of timebase to use. It also applies an optional pre and/or post trigger delay to allow data before and/or after to trigger to be captured.
Five registers are used to program the trace mode:
R8 Trace Register Trace mode selection. R11 Post Trigger Delay Delay after trigger (low byte). R12 Post Trigger Delay Delay after trigger (high byte). R13 Time-base Expansion Time-base expansion factor. R20 Pre-Trigger Delay Buffer prefill before trigger.
The most important trace mode register is the Trace Register R8. The low 4 bits of this register are programmed to with a Trace ID to select one of 6 available modes:
ID Mode Channels Trigger TM0 Simple Trace Mode Single Channel Level Trigger. TM1 Simple Trace Mode Dual Channel (Chop) Enhanced Trigger. TM2 Time-base Expansion Single Channel Enhanced Trigger. TM3 Time-base Expansion Dual Channel (Chop) Enhanced Trigger. TM4 Slow Clock Mode Dual Channel (Chop) Enhanced Trigger. TM8 Frequency Measurement N/A N/A
The values to program to the other trace mode registers depend on the selected mode. Also, the upper 4 bits of the Trace Register R8 are reserved and should always be programmed as zero.