ATSAM4S-XSTK Atmel, ATSAM4S-XSTK Datasheet - Page 18
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ATSAM4S-XSTK
Manufacturer Part Number
ATSAM4S-XSTK
Description
Development Boards & Kits - ARM SAM4S Xplained Pro Starter Kit
Manufacturer
Atmel
Datasheet
1.ATSAM4S-XSTK.pdf
(21 pages)
Specifications of ATSAM4S-XSTK
Product
Starter Kits
Tool Is For Evaluation Of
Xplained Pro
Core
ARM Cortex M4
Interface Type
USB
Operating Supply Voltage
4.4 V to 5 V
Data Bus Width
8 bit, 32 bit
Description/function
For evaluation and prototyping with SAM4S
For Use With
Xplained Pro
5.
5.1
5.2
5.3
Hardware revision history and known issues
Identifying product ID and revision
The revision and product identifier of Xplained Pro boards can be found in two ways, through Atmel Studio or
by looking at the sticker on the bottom side of the PCB.
By connecting a Xplained Pro MCU board to a computer with Atmel Studio running, an information window will
pop up. The first 6 digits of the serial number, which is listed under kit details, contain the product identifier and
revision. Information about connected Xplained Pro extension boards will also appear in the Atmel Kits window.
The same information can be found on the sticker on the bottom side of the PCB. Most kits will print the
identifier and revision in plain text as A09-nnnn\rr where nnnn is the identifier and rr is the revision. Boards with
limited space have a sticker with only a QR-code which contains a serial number string.
The serial number string has the following format:
The kit identifier for SAM4S Xplained Pro is 1803.
Revision 5
On this revision, the SPI clock net is improved to reduce any issues that might be caused by reflections. The
SPI has been removed from the LCD (EXT4 connector) to reduce load on the clock net. The remaining clock
lines have been divided into four terminated nets for each SPI source (EXT1, EXT2, EXT3, and EDBG) and
routed in a star like layout. A series terminator resistor of 43ohm is placed on each clock net, close to the SPI
clock pin. This reduces any issues that might be caused by reflections comming back from unterminated/
unused clock lines. It also reduces the rise/fall time of the clock edges and that will also help to reduce any
reflection issues.
Revision 4
Known issues
●
SAM4S has an on-die series termination of the SPI CLK which makes this signal not usable for a multi
drop clock distribution because all devices along the line will see a fraction of VCC until the signal is
reflected from the end of the transmission line. On the SAM4S Xplained Pro revision 4 this signal is
routed to each extension connector with EXT1 at the end of the line. That means extensions that are
connected along the transission line e.g. EXT3 header is likely to fail due to a non-monotinic edge caused
by relections and the fraction of VCC that is present for a short time until the reflection comes back from
the end of the line.
Workaround:
●
"nnnnrrssssssssss"
n = product identifier
r = revision
s = serial number
By slowing down the clock rise time with a capacitor, and thus effectively increasing the line length at
which point it becomes a transmission line, it is possible to remove the clock issue. A 56pF capacitor
has been mounted on the bottom side of the board between the SPI clock and GND. This however
reduces the maximum SPI clock speed and it is recommended to not run this faster than 30MHz (this
also depends on how much additional capacitance is added by connected extensions and needs to
be checked case by case). The capacitor was added on revision 4 on the bottom side of the EXT3
header.
Atmel SAM4S Xplained Pro [USER GUIDE]
Atmel-42075B-MCU-Atmel SAM4S Xplained Pro-USER GUIDE-03/2013
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