Regulator Output Voltage Selection & Power On; C51 Settings; Int1 Switch; Ea Jumper - Atmel AT89STK-03 Hardware User's Manual

2.2.1 Regulator Output
Voltage Selection &
Power On
2.3

C51 Settings

2.3.1

INT1 Switch

2.3.2

EA Jumper

2.3.3

ALE led

2.3.4

Reset

2.3.5

Crystal

2.4 Features
Description
2.4.1

LEDs Settings

AT89STK-03 Hardware User Guide
Power On/Off
ON
The 3.6V output can be changed by means of R4 resistor (solder side). The output volt-
age equation is:
Vref = 1.20V, R3 = 1MΩ
The INT1 switch can be disabled by removing the solder gout from the solder pad SW36
on the solder side of the CPU demonstration board.
EA Jumper
ON Code fetched from an external memory
OFF Code fetched from MCU's internal memory
The ALE led reports the MCU state. It can be disabled by removing the solder gout from
the solder pad SW4 on solder side of the board.
The push button is provided to generate a warm reset.
The 8 Mhz crystal can be removed in order to be placed next to the appropriate package
(PLCC68 or PLCC28). The load capacitors are disabled by default because the internal
oscillator of the MCU has been designed to work without them. However these capaci-
tors can be enabled by adding a solder gout on the solder pads SW34 and SW35 on the
solder side of the board.
11 LEDs are provided.
Name Color Description
PWR Red Power Supply status
ALE Green MCU activity status - This led is enabled by a solder gout on the solder pad SW4
LED0 Green General purpose led - Connected to P3.2 - Enabled by LED0 jumper
LED1 Green General purpose led - Connected to P3.4 - Enabled by LED1 jumper
OFF
Vref
R4 R3 ×
= -----------------------------
Vout Vref
Description
Hardware Description
Regulator Output Voltage
Selection
3.6V
–
Comments
Default configuration
5V
2-7
7609B–SCR–11/06