Using the STK594 Top Module
2.9Split Power Supply Support
The AT94K FPSLIC devices exist in two different variations, the AL and AX. The AL variation is a 3.3V device manufactured on a 0.35µ process, while the AX variation has a 1.8V core manufactured on a 0.18µ process. The primary difference between the two variations, is that the AX device requires a split power supply, as the I/Os are still pow- ered from a 3.3V supply, while the core operates at 1.8V.
The STK594 supports both AT94K variations. If an AX variant is being used it is neces- sary to supply the proper core to the AT94K device. Figure
Figure 2-11. AT94K Core Voltage Selector
AT94KALAT94KAX
AL | AL |
VDD | VDD |
AX | AX |
2.10XTAL Switch
An oscillator is included on the STK594 for supplying an additional clock to the AT94K FPSLIC device. The XTAL switch selects if the oscillator is connected to the XTAL1 pin, or whether the clock is provided by the STK500.
Figure 2-12 shows a simplified block schematic on how this is implemented.
Figure 2-12. XTAL Block Schematic
FPSLIC
XTAL1 | OSC |
XT1 | |
XTAL2 | XT2 |
2.11Reset Switches The reset switch found on the STK594 is connected to the AT94K’s RESET pin. When pressed, the AT94K device will reset and initiate a configuration download from the con- figuration memory.
The reset switch found on the STK500 is connected to the AVRRESET. When pressed, the embedded AVR microcontroller resets and begins execution at location $0000.
FPSLIC STK594 User Guide