herunterladen
4
Programming in the MAXQ
environment
The MAXQ architecture was developed for application programmers. Each MAXQ microcontroller
includes a hardware debug engine that is tightly integrated with the microcontroller core. The first
chip in this architecture is the MAXQ2000, and this article provides examples and tips on the use of
the IAR Embedded Workbench with the MAXQ2000 Evaluation Kit.
The in-circuit debugging and program-loading features of the MAXQ2000 microcontroller
combine with IAR’s Embedded Workbench development environment to provide C or assembly-
level application development and testing. The hardware-based debug engine and bootloader of
the MAXQ2000 run over a dedicated JTAG port to allow full debugging access with minimal
impact on system resources.
In-circuit debug features
A hardware debug engine, which is tightly integrated with the microcontroller core, controls
the MAXQ2000’s debugging features. This debug engine can invoke service routines in the
on-board utility ROM to support a wide array of debugging features.
• Read access to the integrated flash program memory.
• Read/write access to the on-board data SRAM.
• Read access to the 16 x 16 stack memory.
• Read/write access to all MAXQ2000 system and peripheral registers.
• Step-by-step (trace) program execution.
• Up to four address-based breakpoints to stop program execution at a particular location in code
memory.
• Two data memory-matching breakpoints to stop program execution when a particular location
in data memory is accessed.
• Two register-based breakpoints to stop program execution when write access to a particular
system or peripheral register occurs (cannot be used simultaneously with the data memory
matching breakpoint) and the data being written to the register matches a specified value.
• Password matching function (to unlock the remaining debug functions).
All communication with the debug engine takes place over the MAXQ2000’s dedicated JTAG
Test Access Port (TAP) interface, which is compatible with the JTAG IEEE Standard 1149. This
interface consists of four signals, multiplexed with MAXQ2000 port pins as follows: TMS (Test
Mode Select)—multiplexed with P4.2; TCK (Test Clock)—multiplexed with P4.0; TDI (Test
Data In)—multiplexed with P4.1; and TDO (Test Data Out)—multiplexed with P4.3.
While the JTAG TAP port is dedicated to in-system debug and in-system programming uses, the
four port pins that carry the JTAG TAP port signals may be released for other purposes once
application development is complete. The JTAG port is active by default following reset, but
once running, the application software can deactivate the JTAG port, leaving the four associated
port pins free for other uses.
The JTAG interface and the debug engine operate asynchronously with respect to the
MAXQ2000 core. Communication over the JTAG port need not take place at the same clock rate
that the MAXQ2000 is running, although the frequency of TCK is limited to a maximum of 1/8
the system clock rate for the MAXQ2000.
The in-circuit debugging
and program-loading
features of the
MAXQ2000 micro-
controller combine with
IAR’s Embedded Work-
bench development
environment to provide
C or assembly-level
application develop-
ment and testing.
All communication with
the debug engine takes
place over the
MAXQ2000’s dedicated
JTAG TAP interface,
which is compatible
with the JTAG IEEE
Standard 1149.
AVAILABLE
