branch instructions or during exception entry. See the CoreSight MTB-M0+ Technical Reference Manual
for more details on the MTB execution trace packet format.
Tracing is enabled when the MASTER.EN bit in the Master Trace Control Register is 1. There are various
ways to set the bit to 1 to start tracing, or to 0 to stop tracing. See the CoreSight Cortex-M0+ Technical
Reference Manual for more details on the Trace start and stop and for a detailed description of the MTB’s
MASTER register. The MTB can be programmed to stop tracing automatically when the memory fills to a
specified watermark level or to start or stop tracing by writing directly to the MASTER.EN bit. If the
watermark mechanism is not being used and the trace buffer overflows, then the buffer wraps around
overwriting previous trace packets.
The base address of the MTB registers is 0x41006000; this address is also written in the CoreSight ROM
Table. The offset of each register from the base address is fixed and as defined by the CoreSight MTB-
M0+ Technical Reference Manual. The MTB has four programmable registers to control the behavior of
the trace features:
•
POSITION: Contains the trace write pointer and the wrap bit
•
MASTER: Contains the main trace enable bit and other trace control fields
•
FLOW: Contains the WATERMARK address and the AUTOSTOP and AUTOHALT control bits
•
BASE: Indicates where the SRAM is located in the processor memory map. This register is
provided to enable auto discovery of the MTB SRAM location by a debug agent
See the CoreSight MTB-M0+ Technical Reference Manual for a detailed description of these registers.
11.4. High-Speed Bus System
11.4.1. Overview
11.4.2. Features
High-Speed Bus Matrix has the following features:
•
Symmetric crossbar bus switch implementation
•
Allows concurrent accesses from different masters to different slaves
•
32-bit data bus
•
Operation at a one-to-one clock frequency with the bus masters
Atmel SAM L22G / L22J / L22N [DATASHEET]
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