
Hardware Description
TWR-P1025 Hardware User Guide, Rev. 0
Freescale Semiconductor
5
3.3
System Power
The TWR-P1025 is powered through a barrel connector that provides 5V to the board (and elevators if
present). All further operating voltages are generated via onboard regulators.
The power supply should be rated at 5V @5A.
3.4
Debug Interface
There are two JTAG connectors on board, one for the P1025 (J3) and another for the CPLD(J1). Both use
standard debuggers available from Freescale and Altera respectively. Pin 1 is marked on both connectors.
Refer to the relevant debug tool for operating instructions.
3.5
Accelerometer
An MMA8451Q digital accelerometer is connected to the P1025 through its second I2C interface at
address 0x1C and the accelerometers INT1 signal routed to the P1025 IRQ0.
3.6
Pushbutton and LEDs
The TWR-P1025 features one pushbutton switch connected to a reset circuit. Pressing this button initiates
the reset sequence in the CPLD and performs a HRESET sequence to the P1025 as well as resetting the
Ethernet PHYs, NOR Flash and USB circuitry.
Two LEDs are available to the user through software control. The P1025 GPIO pins, PB27 and PB31 are
routed through the CPLD to control these two LEDs.
3.7
Ethernet
The connectivity between the P1025 and the two Atheros AR8035 GETH PHYs is described in
Table 3-5
&
Table 3-6
and illustrated in
Figure 3-3
.
Table 3-4. CPU Speed Selection
CPU_SPEED
_SELECT0
SW1.7
CPU_SPEED_SELECT1
SW1.8
CORE(0 &1) Speed
(MHz)
QE Speed (MHz)
SYSCLK (MHz)
ON
ON
500
333
66.667
OFF
ON
533
266
66.667
ON
OFF
400
400
66.667
OFF
OFF
384
384
64