Tadpole SPARCbook 3 series, Reference Manual

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Microcontroller Subsystem
12-3
Microcontroller subsystem overview
Assigning low level activites activities to a dedicated microcontroller in
this way releives the main CPU of the burden of trivial activities, ensuring
that it is employed effeciently running applications.
The host CPU and microcontroller communicate via register locations
within the TS102 address space. The CPU places command bytes into the
microcontroller write register, the microcontroller interprets and executes
the command, if possible, and then returns status information via the
microcontroller read register.
12.1.1 Normal operation
Once the initial bootstrapping procedure is complete, the microcontroller
executes its main code loop. This loop incorporates the the following
operations:
1. Checking for host commands from TS102.
2. Checking for keyboard and mouse commands.
3. Scanning the internal keyboard
4. Scanning the internal mouse
5. Detecting characters from an external keyboard
6. Detecting external mouse input
7. Decrementing and checking internal timers
8. Sleep until next interrupt (maximumperiod one centisecond).
Several periodic functions, which are scheduled by the internal counters,
include:
1. Check watchdog timeout
2. Sample temperature
3. Sample battery charge level
4. Update status display
Administration of the link between microcontroller and host is performed
under interrupt control. The main line code transfers any relevant data for
the host into the TS102’s 'read' buffer under an asynchronous
interrupt-controlled transmit mechanism.
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