246
11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
12.5
Functional Description
12.5.1
Test Pin
One dedicated pin, TST, is used to define the device operating mode. When this pin is at low
level during power-up, the device is in normal operating mode. When at high level, the device is
in test mode or FFPI mode. The TST pin integrates a permanent pull-down resistor of about 15
k
Ω,
so that it can be left unconnected for normal operation. Note that when setting the TST pin to
low or high level at power up, it must remain in the same state during the duration of the whole
operation.
12.5.2
Debug Architecture
shows the Debug Architecture used in the SAM4. The Cortex-M4 embeds four func-
tional units for debug:
• SWJ-DP (Serial Wire/JTAG Debug Port)
• FPB (Flash Patch Breakpoint)
• DWT (Data Watchpoint and Trace)
• ITM (Instrumentation Trace Macrocell)
• TPIU (Trace Port Interface Unit)
The debug architecture information that follows is mainly dedicated to developers of SWJ-DP
Emulators/Probes and debugging tool vendors for Cortex-M4 based microcontrollers. For further
details on SWJ-DP see the Cortex-M4 technical reference manual.
Figure 12-4. Debug Architecture
12.5.3
Serial Wire/JTAG Debug Port (SWJ-DP)
The Cortex-M4 embeds a SWJ-DP Debug port which is the standard CoreSight
™
debug port. It
combines Serial Wire Debug Port (SW-DP), from 2 to 3 pins and JTAG debug Port (JTAG-DP),
5 pins.
By default, the JTAG Debug Port is active. If the host debugger wants to switch to the Serial
Wire Debug Port, it must provide a dedicated JTAG sequence on TMS/SWDIO and
TCK/SWCLK which disables JTAG-DP and enables SW-DP.
4 watchpoints
PC sampler
data address sampler
data sampler
interrupt trace
CPU statistics
DWT
6 breakpoints
FPB
software trace
32 channels
time stamping
ITM
SWD/JTAG
SWJ-DP
SWO trace
TPIU
Summary of Contents for SAM4S Series
Page 44: ...44 11100B ATARM 31 Jul 12 SAM4S Series Preliminary ...
Page 412: ...412 11100B ATARM 31 Jul 12 SAM4S Series Preliminary ...
Page 1105: ...1105 11100B ATARM 31 Jul 12 SAM4S Series Preliminary ...
Page 1143: ...1143 11100B ATARM 31 Jul 12 SAM4S Series Preliminary Figure 43 4 64 lead LQFP Package Drawing ...
Page 1145: ...1145 11100B ATARM 31 Jul 12 SAM4S Series Preliminary Figure 43 5 64 lead QFN Package Drawing ...