Functional description
UM1499
Doc ID 022592 Rev 1
2.5 Serial
interface
One serial interface port is available. Typically used as an OS monitor, this port is available
on the J17 connector. It is possible to simulate a cross cable by changing the position of the
J22 jumpers.
Figure 3.
Serial cable setting
2.6
Real time clock (battery powered)
The real time clock (RTC) is powered by an external battery (3V) in order to prevent data
loss even if the main power supply is switched off.
2.7
General power supply
From a 5 V external AC/DC regulator power source, this block generates all the required
voltages as follows:
●
1.2V (Switching regulator PM6641) to supply the internal logic of the SPEAr320S MPU
●
1.8V (Switching regulator PM6641) for the DDR2 memory
●
2.5V (LDO regulator) for the analog portion of SPEAr320S
●
3.3V (Switching regulator PM6641) to supply the other interfaces
A power monitor is also present to provide the general reset of the board.
2.8 Reset
button
A manual reset button (P1) on the top of the board (see
) resets the
microprocessor on the core board.
Nul
Modem
Cable
J22
2
4
1
3
Cross
Cable
J22
2
4
1
3
