ATSAMA5D41A-CU View Datasheet(PDF) - Atmel Corporation
Part Name
Description
MFG CO.
'ATSAMA5D41A-CU' PDF : 1808 Pages View PDF
10.6 Functional Description
10.6.1 Test Pin
One dedicated pin, TST, is used to define the device operating mode. The user must make sure that this pin is tied
at low level to ensure normal operating conditions. Other values associated with this pin are reserved for
manufacturing test.
10.6.2 EmbeddedICE
The Cortex-A5 EmbeddedICE-RT™ is supported via the ICE/JTAG port. It is connected to a host computer via an
ICE interface.The internal state of the Cortex-A5 is examined through an ICE/JTAG port which allows instructions
to be serially inserted into the pipeline of the core without using the external data bus. Therefore, when in debug
state, a store-multiple (STM) can be inserted into the instruction pipeline. This exports the contents of the Cortex-
A5 registers. This data can be serially shifted out without affecting the rest of the system.
There are two scan chains inside the Cortex-A5 processor which support testing, debugging, and programming of
the EmbeddedICE-RT. The scan chains are controlled by the ICE/JTAG port.
EmbeddedICE mode is selected when JTAGSEL is low. It is not possible to switch directly between ICE and JTAG
operations. A chip reset must be performed after JTAGSEL is changed.
Refer to the ARM document ARM IHI 0031A_ARM_debug_interface_v5.pdf for further details on the
EmbeddedICE-RT.
10.6.3 JTAG Signal Description
TMS is the Test Mode Select input which controls the transitions of the test interface state machine.
TDI is the Test Data Input line which supplies the data to the JTAG registers (Boundary Scan Register, Instruction
Register, or other data registers).
TDO is the Test Data Output line which is used to serially output the data from the JTAG registers to the equipment
controlling the test. It carries the sampled values from the boundary scan chain (or other JTAG registers) and
propagates them to the next chip in the serial test circuit.
NTRST (optional in IEEE Standard 1149.1) is a Test-ReSeT input which is mandatory in ARM cores and used to
reset the debug logic. On Atmel Cortex-A5-based cores, NTRST is a Power On Reset output. It is asserted on
power on. If necessary, the user can also reset the debug logic with the NTRST pin assertion during 2.5 MCK
periods.
TCK is the Test ClocK input which enables the test interface. TCK is pulsed by the equipment controlling the test
and not by the tested device. It can be pulsed at any frequency.
10.6.4 Chip Access Using JTAG Connection
The JTAG connection is not enabled by default on this chip at delivery due to the secure ROM code
implementation.
By default, the SAMA5D4 devices boot in Standard mode and not in Secure mode. When the secure ROM code
starts, it disables the JTAG access for the entire boot sequence.
If the secure ROM code does not find any program in the external memory, it enables the USB connection and the
serial port and waits for a dedicated command to switch the chip into Secure mode.
If any other character is received, the secure ROM code starts the standard SAM-BA® monitor, locks access to the
ROM memory, and enables the JTAG.
The chip can then be accessed using the JTAG connection.
If the secure ROM code finds a bootable program, it automatically disables ROM access and enables the JTAG
connection just before launching the program.
SAMA5D4 Series [DATASHEET]
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Atmel-11238C-ATARM-SAMA5D4-Datasheet_12-Jul-16
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