Specifications

Baseboard Interface
30-Dec-2010 CM-X300 Reference Guide Rev 1.31 49
4.3 Baseboard Design Guidelines
Assure that all power pins are connected as specified in ―Power‖ section of this manual.
GND must be implemented by plane, rather than traces.
It is recommended to put several 100 nF and 10/100 uF capacitors between VBAT/VCHRG
and GND near the mating connectors.
It is recommended to connect 3 out of the 4 standoff holes of the baseboard to GND, in
order to improve EMC. The top right hole of the baseboard should be isolated, for
compatibility with future CAMI modules (referring to module's orientation drawings).
Except of power connection, no other connection is mandatory for CM-X300 operation. All
powerup electronics and all required pullups/pulldowns are found on the module.
If for some reason you decide to place external pullup or pulldown resistor on certain signal
(for example - on GPIO's), check the documentation of that signal as provided in this
manual. Certain signals have on-board pullup/pulldown resistors required for proper
initialization. Overriding their values by external components will disable board operation.
You must be familiar with signal interconnection design rules. There are many sensitive
groups of signals. For example:
 Ethernet and USB signals must be routed in differential pairs and by controlled
impedance trace.
 Audio input must be decoupled from possible sources of baseboard noise.
 Local bus signals must be buffered in most cases.
Be careful when placing component under the CM-X300 module. CAMI connector
provides 4mm mating height. Bear in mind that there are components on the underside of
the CM-X300. In general, maximum allowable height for components placed under the
CM-X300 is 2mm.
See the SB-X300 baseboard reference design schematics.
4.4 Baseboard Troubleshooting
Using grease solvent and soft brush, clean contacts of mating connectors of both module
and baseboard. Remainders of soldering paste can prevent proper contact. Take care to let
the connectors and the module dry entirely before re-applying power – otherwise corrosion
may occur.
Using oscilloscope, check voltage levels and quality of VBAT and VCHRG power
supplies. It should be as specified in ―power‖ section. Check that there is no excessive
ripple or glitches. First perform the measurements without plugging in the module. Then
plug in the module and measure again. Measurement should be performed on the pins of
mating connector.
Using oscilloscope verify that GND pins of mating connector are indeed at zero voltage
level, and there is no ground bouncing. Module must be plugged in during the test.
Create "minimum system" - only power, mating connectors, the module, and serial
interface.
Check if the system starts properly. In system larger than minimum, the possible sources of
disturbance could be:
 Devices improperly driving local bus
 External pullup/pulldown resistors overriding module‘s on-board values, or any
other components creating the same "overriding" effect.
 Bad power supply.