050-1BA00 : response time calculation of the Latch input
| Version Number | Description |
|---|---|
| 1.0 | initial version |
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1. Initial data and filter principle
The 050-1BA00 has an input delay of 0.8µs on its channels.
Additionally, to reduce the effect of electrical noise, a filter is added on all of its channels with a predefined frequency selected by the user as follows:
These filters add an extra delay (see explanation below). Depending on the filter time value selected, the following delay is expected:
When the filter setting is 0x00, the module records a new sample every 0.667µs.
When the filter setting is 0x02 (the highest value available to the user), the system waits 4 samples (0.667[µs] * 4[samples] = 2.667[µs]) of the same value to acknowledge a change of edge and then count a change. This filter allows better immunity against electrical noise.
Below is an example of the time delay between the input signal and the frequency setting for a square Wave signal of 100kHz:
2. Calculation of the Latch response time
To calculate the response time between when the signal is received on a channel and when the value is recorded, the user should use the following formula:
<Response time CH_X> = <Input delay> + <filter delay>.
Then to have the exact response time, the following formula applies:
<Latch accuracy> = <Response time latch channel> - <Response time track A/B>
Note:
A positive result value means a delay, and a negative value means a prefetch (= record a value before the latch happens)
Example:
- In case Input Frequency track A and B filter = 100kHz, the response time will be : 0.8µs + 2,667µs = 3,467µs
- In case Input latch frequency filter is also defined at 100kHz, then the accuracy is = 3,467µs -3,467µs = 0µs.
- NOTE: 0µs is the theoretical value, there is always a jitter. The jitter max value is <1µs