Note 1: For the AT88SA100, AT88SA102, and the AT88SA10HS devices, 5.0V is
required to burn the fuses.
Note 2: The AT88Microbase is shipped with a 16MHz crystal, which allows the
AT90USB1287 on-chip USART to obtain the 230.4K baud rate (-3.5%
error) required to communicate with a CryptoAuthentication device. The
16MHz crystal requires that
5.5VCC5.4
. To operate the
AT88Microbase below 4.5V, the 16MHz crystal must be replaced with an
8MHz crystal. The ABM3B-8.000MHZ-B2-T
8MHz crystal is a drop-in
replacement.
3.2.2 Power LED, “LEDP”
The blue LED (LEDP) is always lit when power is applied to the AT88Microbase regardless of the
voltage supply.
Figure 4. Power on LED “LEDP”
3.3 RESET
Although the AT90USB1287 has its on-chip RESET circuitry, (c.f. AT90USB1287 Datasheet,
section “System Control and Reset”), the AT88Microbase provides two additional means to reset
the AT90USB1287.
3.3.1 Power-on Reset
The on-board RC network acts as power-on RESET.
3.3.2 RESET Push Button
By pressing the RESET push button on the AT88Microbase, a warm RESET of the AT90USB1287
AVR is performed.
Figure 5. RESET Push Button (AVR RESET) Implementation
