Atmel ARM-Based Evaluation Kit for SAM4S16C, 32-Bit ARM® Cortex® Microcontroller ATSAM4S-WPIR-RD ATSAM4S-WPIR-RD Data Sheet
Product codes
ATSAM4S-WPIR-RD
271
SAM4S Series [DATASHEET]
Atmel-11100G-ATARM-SAM4S-Datasheet_27-May-14
When the Serial Wire Debug Port is active, TDO/TRACESWO can be used for trace. The asynchronous TRACE
output (TRACESWO) is multiplexed with TDO. So the asynchronous trace can only be used with SW-DP, not
JTAG-DP.
SW-DP or JTAG-DP mode is selected when JTAGSEL is low. It is not possible to switch directly between SWJ-DP
and JTAG boundary scan operations. A chip reset must be performed after JTAGSEL is changed.
13.5.3.1 SW-DP and JTAG-DP Selection Mechanism
Debug port selection mechanism is done by sending specific SWDIOTMS sequence. The JTAG-DP is selected by
default after reset.
Switch from JTAG-DP to SW-DP. The sequence is:
̶
Send more than 50 SWCLKTCK cycles with SWDIOTMS = 1
̶
Send the 16-bit sequence on SWDIOTMS = 0111100111100111 (0x79E7 MSB first)
̶
Send more than 50 SWCLKTCK cycles with SWDIOTMS = 1
Switch from SWD to JTAG. The sequence is:
̶
Send more than 50 SWCLKTCK cycles with SWDIOTMS = 1
̶
Send the 16-bit sequence on SWDIOTMS = 0011110011100111 (0x3CE7 MSB first)
̶
Send more than 50 SWCLKTCK cycles with SWDIOTMS = 1
13.5.4 FPB (Flash Patch Breakpoint)
The FPB:
Implements hardware breakpoints
Patches code and data from code space to system space.
The FPB unit contains:
Two literal comparators for matching against literal loads from Code space, and remapping to a
corresponding area in System space.
Six instruction comparators for matching against instruction fetches from Code space and remapping to a
corresponding area in System space.
Alternatively, comparators can also be configured to generate a Breakpoint instruction to the processor core
on a match.
13.5.5 DWT (Data Watchpoint and Trace)
The DWT contains four comparators which can be configured to generate the following:
PC sampling packets at set intervals
PC or Data watchpoint packets
Watchpoint event to halt core
The DWT contains counters for the items that follow:
Clock cycle (CYCCNT)
Table 13-2.
SWJ-DP Pin List
Pin Name
JTAG Port
Serial Wire Debug Port
TMS/SWDIO
TMS
SWDIO
TCK/SWCLK
TCK
SWCLK
TDI
TDI
-
TDO/TRACESWO
TDO
TRACESWO (optional: trace)