668-0011 Rabbit Semiconductor, 668-0011 Datasheet - Page 228

• Manufacturer Part Number: 668-0011
• Description: IC MPU RABIT3000A 55.5MHZ128LQFP
• Manufacturer: Rabbit Semiconductor

Specifications of 668-0011

• Rohs Status: RoHS non-compliant
• Processor Type: Rabbit 3000 8-Bit
• Speed: 55.5MHz
• Voltage: 2.5V, 2.7V, 3V, 3.3V
• Mounting Type: Surface Mount
• Package / Case: 128-LQFP
• Features: -
• Other names: 316-1043

26.3.2 Mixed System/User Mode Operation
This mode is similar to the previous mode, but with some portions of the program written
for System Mode — for example, peripheral interrupts where latency is critical. By keep-
ing the System Mode code sections small, potential system crashes are still minimized.
Figure 26-2 shows an overview of this level of operation.
26.3.3 Complete Operating System
This section describes a “full” use of the System/User Mode — separating all common
functions into a System Mode “operating system” while letting the application-specific
code run in the User Mode. By default, the System Mode handles all peripherals and inter-
rupts, as well as high-level interfaces such as a flash file system. However, the processor
will be running the application code in the User Mode most of the time.
The application code can request direct access to a peripheral and/or interrupt from the
System Mode. If allowed, the System Mode can create an interrupt vector as described in
Section 26.3.7 that will execute the user code interrupt handler.
When the application code wants to perform an action that is controlled by the System
Mode, it can request the particular action by loading the appropriate value into HL and
executing SYSCALL . This requires generating a list of all the actions that the application
code would want to do, assigning values to each action, and implementing a SYSCALL
handler in the System Mode that parses the value passed to it and calls the appropriate
function.
Write protection should be enabled (User Mode only) for all blocks containing system
code and data as well as any critical memory regions.
If any critical interrupts occur (stack limit violation, system mode violation, write protec-
tion violation), System Mode handlers can perform any of a number of operations: restart
the application code, signal another device, halt operation, and so on.
218
Figure 26-2. System/User Mode Setup for Mixed Operation
System Mode
Time-critical
interrupts
interrupts
Critical
Return from interrupts
Interrupts
Critical
Rabbit 3000 Microprocessor User’s Manual
User Mode
User-defined
Application
interrupts
code