st20-gp6 STMicroelectronics, st20-gp6 Datasheet - Page 75

• Manufacturer Part Number: st20-gp6
• Description: Gps Processor
• Manufacturer: STMicroelectronics

14 Diagnostic controller
The ST20 Diagnostic Controller Unit (DCU) provides a means for booting the CPU, and for the con-
trol and monitoring of all systems on the chip, via the standard IEEE 1194.1 Test Access Port. The
Test Access Port is described in Chapter 23. The DCU includes on-chip hardware with ICE (In Cir-
cuit Emulation) and LSA (Logic State Analyzer) features to facilitate verification and debugging of
software running on the on-chip CPU in real time. It is an independent hardware module with a pri-
vate link from the host to support real-time diagnostics.
14.1 Diagnostic hardware
The on-chip diagnostic controller assists in debugging, while reducing or eliminating the intrusion
into the target code space, the CPU utilization, and impact on the application. As shown in
Figure 14.1, the DCU and TAP provide a means of connecting a diagnostic host to a target board
with a suitable JTAG port connector and interface.
The diagnostic controller provides the following facilities for debugging from a host:
When running multi-tasking code on the target, one or more processes can be single-stepped or
stopped while others continue running in real time. In this case, the running threads can be inter-
rupted by incoming hardware interrupts, with a low latency.
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control of target CPU and subsystems including CPU boot;
hardware breakpoint, watchpoint, datawatch and single instruction step;
complex trigger sequencing and choice of subsequent actions;
non-intrusive jump trace and instruction pointer profiling;
access to the memory of the target while the device is powered up, regardless of the state
of the CPU;
full debugging of ROM code.
analyzer
Logic
state
Host
Figure 14.1 Debugging hardware
interface
Host
access
Test
port
ST20
Diagnostic
controller
ST20-GP6
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