ST18AU1_DS View Datasheet(PDF) - STMicroelectronics
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MFG CO.
'ST18AU1_DS' PDF : 87 Pages View PDF
ST18-AU1
15 EMULATION UNIT
The emulation unit (EMU) performs functions dedicated to emulation and test through the
external IEEE 1149.1 JTAG interface. Refer to Chapter 14 for details on the JTAG test access
port.
The emulation and test operations are controlled by the JTAG Test Access Port (TAP) and the
emulator by means of dedicated control I/Os.
Emulation mode can entered in one of two ways:
• Asserting ERQ input pin low.
• Meeting a valid breakpoint condition or executing an instruction in single step
mode.
The PC board emulator is able to display the processor status (memories and registers) and
restore the context.
The emulation resources (see Figure 15.1) include:
• Four breakpoint registers (BP0-3) which can be affected by Program or Data
memory.
• Breakpoint counter (BPC).
• Program counter trace buffer (PCB) able to store the address of the 6 last
executed instructions.
• Three control registers for breakpoint condition programming (BC0-1 and
ECS).
• Control logic for instruction execution through the PC-board emulator control.
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