Operation
3-2
3.1
Operation
Use of ISD51 is straightforward.
1) Copy the ISD51.A51 and ISD51.H files, provided by Keil, to your project
folder.
2) Add ISD51.A51 to the
µ
Vision2 project.
3) Add ISD51.H to the C module that contains the main C function.
4) Check the configuration settings in ISD51.H and modify them if necessary.
5) Add serial port and baud rate initialization code for the on-chip UART to
your C main function.
6) Add an appropriate ISD51 startup function to your C code.
With ISD51, a serial interrupt function for the TUSBxxxx UART is added to your
user program. When code is executed with the
µ
Vision2 debugger, the 8052
enters this interrupt function. While program execution is stopped, the 8052
program runs only the ISD51 interrupt, allowing communication with the
debugger. When the debugger commands the interrupt function to resume,
the 8052 exits the ISD51 interrupt function and executes the user program.
Code execution can be controlled using software breakpoints. If breakpoints
are set, the 8052 enters the interrupt routine after each instruction, which
checks whether a breakpoint address has been reached. If so, it connects to
the
µ
Vision2 debugger; otherwise, it returns execution to the program.
3.2
Resource Requirements
ISD51 requires some of the system resources to execute:
-
One of the on-chip UARTs
-
About one-half Kbyte program code
-
Six bytes stack space
-
One byte of IDATA RAM
-
Two bytes of IDATA RAM for each software breakpoint, defined top down
from 0xFF
An effect of running ISD51 is a slowdown in execution speed. Software
breakpoints, when used, slow execution on the order of 100
×
. For portions of
code that are negatively affected by this slowdown or are speed-critical, ISD51
can be enabled/disabled programmatically, thereby allowing selective use of
the feature.
Summary of Contents for TUSB2136
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