Unterschiede

Hier werden die Unterschiede zwischen zwei Versionen angezeigt.

--- project:hgg:hardwaredoc:how_the_timing_bus_works [2012-03-17 20:55] – angelegt reloc0
+++ project:hgg:hardwaredoc:how_the_timing_bus_works [2012-10-03 18:53] (aktuell) – alte Version wieder hergestellt 109.192.98.64
@@ Zeile 25: / Zeile 25: @@
 Tweak:
-   If some module does not need the fasttime information becuase the developer feels that a 1 second resolution is good enough, it can recieve this packet into a 40-bit register.
+If some module does not need the fasttime information becuase the developer feels that a 1 second resolution is good enough, it can recieve this packet into a 40-bit register.
@@ Zeile 39: / Zeile 39: @@
 Within a Ground-station the speed of the oscilator should be known and can assumed to be constant but clock drifts.
+===== PPS - a new second begins =====
+When the PPS is activated (Active Low), the previously sent slowtime becomes valid. The local counters for the fastclock should be resetted.
+====== Measuring the Time with the Timing bus ======
+This describes how it would be for a Fast-Timing Module, for a module needing only the slow time information, ignore everything about the fast time and read the Tweak from the SLOWCLK section.
+Prerequisites:
+  * There is a +1 Counter with 32 bits that counts up on every clock tick of the FASTCLK.
+  * The SLOWCLK Information is being put into a Register
+  * When PPS comes, the counter is being reseted and restarts from 0. The SLOWCLK Information from the Bus is latched into a register CURTIME.
+When the event comes in, the following is happening:
+  - Latch CURTIME + the current Value of the Counter into a Parallel-in-Serial-Out Register (makes 72+32 bit).
+  - Process the event
+  - Get the Information from the PISO
+  - Send all information to the target over the
+What you get is a 40-bit timestamp of the current time and the number of clock ticks within the current second. With a known FASTCLK frequency you can easily calculate the fraction of a second and thus complete the timestamp to SECOND and FRACTION OF SECOND values.
+The maximum resoltution is dependent on the oscilator speed. Eg: 10Mhz FASTCLOCK makes 100ns resolution.