Format Of X-Modem Upload Files; Power Over Ethernet; Real-Time Clock; Known Issues - PC Engines WRAP User Manual

Format of X-Modem upload files

The uploaded file is stored starting at offset 1000:0. The first two bytes are a signature, and should
be TB. Setup will do a far call to 1000:2 if the signature is detected. ES:DI points to the end of the
uploaded file in memory.

Power over Ethernet

WRAP implements a passive power over Ethernet scheme, using the unused pairs of LAN1 for
power. Power can be injected using a passive POE splitter such as PC Engines POE.1A.
When power is fed in through POE, it is possible to "steal" unregulated power through the DC jack.
Please note that this port is not fused. The POE input diode is rated for a current of 3A. Please
keep in mind that any EMI energy injected on this port will go out through the Ethernet cable
without further filtering.

Real-Time Clock

WRAP does not include a battery backup for the real-time clock (RTC).
The A3 stepping of the SC1100 CPU had a problem with the 32768 Hz oscillator, leading to
potential RTC inaccuracy. This version also was sensitive to ESD on the battery voltage pin.
A backup battery can be connected as follows:
WRAP.1C / .1D: Add a 100 ohm, 0603 resistor in location R5, replace the 0 ohm resistor in location
C105 (bottom side) with a 0.1uF 0603 capacitor, install a 2 pin header in location J1. Connect 3V
Lithium battery to J1, observing the polarity marks.
WRAP.2B / .2C: Connect 3V battery to J7 pin 7 (positive) and pin 8 (negative).
SC1100 is specified for a battery voltage of 2.4 to 3.6V, drain current 7 to 30 A. At 30 A, a
CR2032 Lithium coin cell will last only about a year – please consider a larger CR123 Lithium (often
used in cameras).

Known issues

Reset may not work reliably on very short power interruptions. Please make sure that power remains
off for at least a second.
WRAP router platform 11 2/13/2007