ATSTK500 Atmel, ATSTK500 Datasheet - Page 30

• Manufacturer Part Number: ATSTK500
• Description: PROGRAMMER AVR STARTER KIT
• Manufacturer: Atmel
• Series: AVR®r
• Type: MCUr

Specifications of ATSTK500

• Contents: Board, Cable, CD and Documentation
• Data Bus Width: 8 bit
• Interface Type: RS-232
• For Use With/related Products: Atmel AVR Devices
• For Use With: ATADAPCAN01 - EXTENSION CAN ADD-ON TO STK500/1
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

1925C–AVR–3/03
Hardware Description
3.8.4
3-20
Clock Settings,
XTAL1 and OSCSEL
When connected to an external system, there is often an external pull-up resistor con-
nected to the reset line. A typical reset connection is shown in Figure 3-27.
Figure 3-27. External Reset Connection
If the external pull-up resistor is too low (<4.7 kΩ), STK500 will not be able to pull the
RESET line low.
STK500 includes several clock options for the target AVR. Setting the jumpers XTAL1
and OSCSEL controls the clock selections. OSCSEL determines what signal to route to
the XTAL1 pin of the AVR.
When the XTAL1 jumper is connected, the STK500 internal clock system is used as
main clock to the target AVR. When XTAL1 jumper is not mounted, the internal clock
system is disconnected. This allows external clock signals or crystals to be used as tar-
get clock source for the AVR. Figure 3-28 illustrates the XTAL1 jumper option.
Figure 3-28. XTAL1 Jumper Options
When the XTAL1 jumper is not mounted, an external clock source or crystal can be con-
nected to the PORTE header. This is shown in Figure 3-30.
Jumper Mounted
On-board XTAL1 Signal Connected (Default)
Jumper not Mounted
On-board XTAL1 Signal Disconnected
OSCSEL
OSCSEL
RESET
RESET
XTAL1
XTAL1
AREF
AREF
R (4.7 kohm)
C (10 nF)
RESET
AVR STK500 User Guide