suservo: note requirement to stop servo when accessing state

As already mentioned in the gateware.

One alternative would be to detect address collisions and
stall the read for one cycle.

Note that there will in general not be a consistent view of the servo
state unless the servo is stopped.

close #1337
This commit is contained in:
Robert Jördens 2019-07-08 18:30:19 +02:00
parent f8dba7ae35
commit f7e10759dc
1 changed files with 16 additions and 0 deletions

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@ -195,6 +195,10 @@ class SUServo:
This method does not advance the timeline but consumes all slack.
If reading servo state through this method collides with the servo
writing that same data, the data can become invalid. To ensure
consistent and valid data, stop the servo before using this method.
:param adc: ADC channel number (0-7)
:return: 17 bit signed X0
"""
@ -225,6 +229,10 @@ class SUServo:
This method does not advance the timeline but consumes all slack.
If reading servo state through this method collides with the servo
writing that same data, the data can become invalid. To ensure
consistent and valid data, stop the servo before using this method.
The PGIA gain setting must be known prior to using this method, either
by setting the gain (:meth:`set_pgia_mu`) or by supplying it
(:attr:`gains` or via the constructor/device database).
@ -454,6 +462,10 @@ class Channel:
This method does not advance the timeline but consumes all slack.
If reading servo state through this method collides with the servo
writing that same data, the data can become invalid. To ensure
consistent and valid data, stop the servo before using this method.
:param profile: Profile number (0-31)
:return: 17 bit unsigned Y0
"""
@ -468,6 +480,10 @@ class Channel:
This method does not advance the timeline but consumes all slack.
If reading servo state through this method collides with the servo
writing that same data, the data can become invalid. To ensure
consistent and valid data, stop the servo before using this method.
:param profile: Profile number (0-31)
:return: IIR filter output in Y0 units of full scale
"""