Logic Analyzer core: Timers

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Timer limits are very simple. You write a 36 bit value. Lower 32 bits to trigger register 0x38/0x3A. Upper 4 bits to trigger register 0x39/0x3B. The fpga reference clock is 100Mhz, so each timer tick corresponds to 10ns.


Figure 17 - Timer

The 36-bit timers have a range from 10ns to 687 seconds (over 11 minutes). Timers are started, stopped, and cleared under control of the trigger sequencer.

6.1 Example (Timer Initialization)

void write_trigger_limit (int timersel, uint64_t value)
  write_select (0x38 + (timersel&1)*2);
  write_chain (value & 0xFFFFFFFF);
  write_select (0x39 + (timersel&1)*2);
  write_chain (value>>32);

Figure 18 - Initialize Timer Values

License note

This document is Copyright © 2011 Ian Davis
Released under the  GNU General Public License