letATwork II

High Tech ATmega 103 / 128 Microboard

[ Connection Pins | ISP Interface | Technical Data | Order ]

The Atmel ATmega103 and it's descendant ATmega128 are among the most powerful 8bit micro controllers. They are available in TQFP package, so we took the chance to mount them on 45 x 46 sq.mm, add a reset circuit, an "in-system programming" (ISP) socket and 5V voltage regulator. On letATwork revision II you also have an RS232 level output.

This board is not just an adapter but a complete motherboard for the ATmega 103 / 128. As soon as you connect power supply and ISP plug, you can start filling the 128 kByte program flash of the ATmega.

Give your developments new impulses, convince yourself ...
simply let AT work!

letATwork II mikroboard


The pin connections

All Atmel ATmega 103 / 128 pins are available at two 0.1" pinout double rows, i.e. there are no restrictions for future extensions. For example external RAM can be added effortlessly.
All 6 ports and ADC inputs are available. Additionally there is a 5V (50mA) output which is useful to supply your external circuits.

At letATwork revision II you can select either TTL or RS232 level on the PE0 / PE1 output pins by setting jumpers.

A general view over letATwork is provided by the following block sketch:

letATwork block scheme

Because of the special qualities of the 4 layer design the letATwork II is especially well suitable for the new ATmega128 (which can be clocked up to 16 MHz and is therefore more sensitive to interferences / disturbances).

The letATwork II with ATmega103-6AI can be purchased in a 3.6864 MHz (for UART use), 4 MHz and a 6 MHz version. All modules are equipped with the 6 MHz version of the ATmega103, so an upgrade is easy.
The ATmega128-16AI version is equipped with 8 MHz or 16 MHz crystal. Please ask for alternative crystal frequencies.

The board is first choice for projects that have to be developed on short time-scales. Applications reach from display controls (especially for memory intensive graphic displays), applications in the telemetry sector, complex controlling tasks up to extending robot instructions.


The ISP Interface

The letATwork has got a 2x5 pin programming connector which enables 100 percent in system programming. A multiplexer at the bottom of the board switches the ATmega pins during programming and a LED indicates programming activity.

letATwork programming adapter

Which Programming Adapter can be used?

Which Programming Software is useable for letATwork?

Each programming tool supporting the SPI-programming-mode of the ATmega can be used; e.g. Atmel AVR Studio, the free PonyProg, the ISP function of the Codevision C Compiler or the BASCOM-AVR basic compiler and several other development environments with ISP are applicable.


Technical Data

The ATmega103-6AI

  • AVR risc architecture
  • 121 commands (mostly single cycle)
  • 6 MIPS at 6MHz
  • 128 KByte program flash, 4KByte SRAM, 4KByte EEPROM (all inside the CPU)
  • Master/Slave SPI interface
  • UART (up to 115000 Baud)
  • real time clock (RTC) with 32 KHz crystal
  • 8 channel 10 Bit A/D converter
  • 6 ports (32 I/O, 8 output, 8 input)
  • extended temperature range
  • external and internal interrupt sources (timer,comp,ext ..)
  • further info@Atmel home page:

    ATmega103(L) Summary (12 pages, 09/01)
    ATmega103(L) (Complete) (134 page, 09/01)
    ATmega103(L) Rev. L Errata (4 pages, 09/01)

  • The ATmega128

  • ATmega128(L) Preliminary Summary (16 pages, 09/01)
    ATmega128(L) Preliminary (Complete) (331 pages, 09/01)


    We would appreciate any contribution concerning applications of the letATwork.
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