TC1796
Peripheral Units (Vol. 2 of 2)
Analog-to-Digital Converter (ADC)
User’s Manual
25-22
V2.0, 2007-07
ADC, V2.0
multiplexer, and the settings of the ADC’s resolution. If the back-up register contains
valid conversion information, the arbiter reads from the back-up register instead from the
channel injection control register. Thus, the previously cancelled conversion participates
in arbitration once again. A new conversion requested via the conversion request control
register will be performed after the request in the back-up register is served.
The request bit of the channel injection control register and the backup register can be
cleared under software control. Clearing the arbitration participation bit clears either the
request bit in the request register (if the back-up register contains no request) or the
request bit in the back-up register (if the back-up register contains a valid request).
As already mentioned, “Channel Injection” generates sequential conversion requests for
analog channels either with the Inject-Wait or the Cancel-Inject-Repeat functionality.
•
Channel Injection with Inject-Wait
provides the means to wait until the current
conversion with higher priority is finished before the requested conversion is injected.
•
Channel Injection with Cancel-Inject-Repeat
“Cancels” a currently performed
conversion, “Injects” the requested conversion, and finally “Repeats” the previously
cancelled conversion. The Cancel-Inject-Repeat feature is enabled if bit
CHIN.CIREN is set. When using this feature, the currently performed conversion is
cancelled if its source arbitration level is lower than the source arbitration level of
channel injection. If a currently performed conversion is cancelled, a new request is
generated for this conversion. Thus, the previously cancelled conversion participates
in the arbitration again.
The following examples provide an overview on the behavior of the conversion request
source “Channel Injection”.
shows the functionality of conversion requests generated by “Channel
Injection” with Inject-Wait feature. The conversion requested with a source-arbitration-
level of ‘L3’ waits until the currently performed conversion with a source-arbitration-level
of ‘L1’ is finished. The second channel injection request is delayed until both conversions
requested with a source-arbitration-level of ‘L2’ are finished.