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Distributor of Equinox Technologies: Excellent Integrated System Limited
Datasheet of ISPNANO S3 KIT - ISP PORTABLE PROGRAMMER
Contact us: sales@integrated-circuit.com Website: www.integrated-circuit.com
1.3 Atmel AVR microcontroller - SPI connections
Most Atmel AVR microcontrollers use the standard "SPI" pins for In-System Programming – see
diagram (a) below. However, certain ATmega devices actually use the UART pins (RXD / TXD) for In-
System Programming – see diagram (b) below. Please refer to Application Note AN101 for detailed
instructions of how to program an Atmel AVR microcontroller via the SPI interface.
(a) Standard AVR "SPI" programming pin-out
PROG_VCC
PROG_RESET
PROG_MOSI
PROG_SCK
PROG_MISO
PROG_GND
The table below details the connections for programming Atmel AVR microcontrollers via the SPI
Interface.
Pin
Programmer
No
Pin name
1 + 2
TARGET_VCC
3 + 4
TARGET_EXT_VCC P
5 + 6
PROG_GND
12
Programmer I/O3
13
Programmer I/O2
14
Programmer I/O1
16
PROG_RESET
O - Output from programmer to Target Device
I - Input to programmer from Target Device
P - Passive e.g. GROUND and power rails
N/C - Not connected
Reset
Circuit
Vcc
RESET
MOSI
Atmel
S
P
ATmega
I
AVR
SCK
P
Microcontroller
O
(Standard
R
T
pin-out)
MISO
Vss
Programmer
Connect to
Input /
pin on
Output
Target System
P
TARGET_VCC
See notes.
P
Signal GROUND
(0V)
I/O
SPI - SCK
I/O
SPI - MISO
I/O
SPI - MOSI
O
RESET
(b) AVR "UART" programming pin-out
PROG_VCC
PROG_RESET
PROG_MOSI
PROG_SCK
PROG_MISO
PROG_GND
Notes
Target VCC
Target External VCC
Signal Ground Connection
SPI - Serial Clock Signal
SPI – Master In Slave Out
SPI – Master Out Slave In
Target RESET control pin
Reset
Circuit
Vcc
RESET
RXD
Atmel
S
P
ATmega
I
AVR
SCK
P
Microcontroller
O
(UART
R
T
pin-out)
TXD
Vss
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