TC1796
Peripheral Units (Vol. 2 of 2)
Analog-to-Digital Converter (ADC)
User’s Manual
25-14
V2.0, 2007-07
ADC, V2.0
25.1.2.5 Parallel Conversion Request Source “Software”
The conversion request source “Software” makes it possible to generate conversion
request under software control, as shown in
.
Figure 25-8 Conversion Request Source “Software”
One or more request bits can be set at a time by software, resulting in a conversion
request for the designated analog channel(s). Writing to the register REQ0 automatically
loads its contents into register SW0CRP. The contents of REQ0 remains unchanged
after a load operation. A trigger pulse (SW0TR = 1) also leads to this load operation.
If at least one bit is set in REQ0 when the software gating input SW0GT = 1, the
arbitration participation flag AP.SW0P is set. This informs the arbiter to include the
conversion request source “Software” in the arbitration. If “Software” is the arbitration
winner, a conversion is started for the conversion request within register SW0CRP with
the highest channel number. Starting a conversion causes the conversion request bit in
register SW0CRP to be cleared by the arbiter. If a currently running “Software” initiated
conversion is cancelled, the arbiter sets the corresponding conversion request bit in
registers SW0CRP for this channel. If all pending conversion requests are processed,
the arbitration participation flag AP.SW0P becomes 0.
The contents of register SW0CRP can be reset under software control either bit-wise by
writing a 0 to the corresponding bit position in register REQ0 or globally by clearing the
“Software” arbitration participation flag.
MCA06011
REQ0
SW0CRP
16
AP.SW0P
Reset by Software
Clear all
on reset by
software
Write to Register REQ0
Set/Reset by Arbiter
Trigger Input
SW0TR
&
Gating Input
SW0GT
Set
≥
1
16
16
≥
1