Home Products Prices Site Map Order Contact What's New Books Free Files Links FAQ
Dontronics Home Page  SIMM100 SimmStick  compatible for the AT90S8535

Bottom of Page
Order Now Catalogue
This new 2" SimmStick compatible board for the Atmel AVR AT90S8535 was designed in Sweden by Lars Wictorsson of Lawicel. It is the same price as all other 2" SimmSticks available from Dontronics.

26-Sep-2002 Lars Wictorsson
Regading SIMM100, it works fine with 8535, Mega163, Mega323, Mega16 & Mega32. I2C bus is in the wrong place, but of course, I didn't know about the Mega's when I made the SIMM100 board, since it was before their time.

SimmStick compatible

The picture above shows 2 Simm100 boards (component and solder side)
for the Atmel AVR microcontroller type AT90S8535.

The picture above shows the Simm100 board mounted with an AT90S8535, MAX232, MAX701, Reset button and IDC connectors for RS-232, ADC and ISP (In System Programmable). To improve EMI, the board has a ground layer and a separate ground layer for the ADC for a stable Analog Conversion.

REV.A Schematics

REV.B Schematics

Click on the Schematics to enlarge

Download SIMM100 Manual

SIMM100 REV.B was made in August 2000.
  • 2 wires for RS232 added to the standard A1/A2 pins.
  • New RESET devices added
The picture above left shows that it is now possible to add a standard Brown out reset device (similar to those used on e.g. DT103/104/107). Since the normal MAX701 has a separate input pin and an output pin for reset, you need to connect these signals together and that is done with the jumper.

Assembling Instructions

For minimum operation you have to install IC1, XTAL, C1, C2, C3, C11, C12 & R3. The XTAL can be exchanged to a resonator, then C2 and C3 can be omitted. When using the RC Reset (C12 / R3), you also need to install jumper J6 (Rev.B board only) or jumper pin 1 & 6 of IC3 (Rev.A board only) , so the reset signal reaches the microcontroller. You can also add the PB1 pushbutton for a manual RESET if you do not have that on any other place (like e.g. on the DT003/DT006).

If you need a bit better RESET (due to that you have other hardware in the system like EEPROM etc. and you want to guarantee that the microcontroller doesn't write to the EEPROM when voltage is too low, then you shall install the Brownout device Q1 and the resistor R6 (Rev.B board only).

If you need the best RESET performance with a delayed RESET of 200-300mS, you should not install C12 / R3 or Q1 / R6, instead just install the IC3 (MAX701).

Then if you need ISP (In System Programmable) with a Kanda / Atmel STK200 compatible programmer, you need to install J2 and if you like to have indication when programming etc. also R2 and LD1.

If you want to use the ADC of the AT90S8535, then install R1 and C4 and optionally the J2 IDC connector. Jumper J1 is by default applying 5VDC to the AREF of the ADC and if you need any other reference voltage, cut that wire open on the board and install J1, so you can select a different reference voltage. pin 9 on the J1 connector could then be used for applying the new voltage reference. There is also a very small Prototype/Experiment area and one of the pads are connected to 0VDC (GND) and the other 5VDC (VCC).

To add on board RS-232, you need to install IC2, C5, C6, C7, C8, C9 and the J4 IDC connector. The J4 IDC connector is pin compatible with the SLI-OEM from Wirz, so adding a straight ribbon cable between the SIMM100 and the SLI-OEM makes it simple and easy to use a serial LCD.

If you do not have access to 5VDC and would like to use e.g. 9-12VDC then install the voltage regulator V1 and capacitor C10.

Finally the 2 user definable / general purpose LEDs (LD2 & LD3) plus the resistors for them (R4 & R5) could be mounted and controlled via PC0 & PC1 of the microcontroller, note that they sink current into the microcontroller, so turning them on need a LOW output (0VDC) and turning them off needs a HIGH output (5VDC).

J5 is also a small 4 pin connector for the rest of the PD port (PD4-7) that isn't routed out the the SimmStick bus.

Component Values
IC1 Microcontroller type AVR AT90S8535 or simular
IC2 RS-232 Tranceiver type MAX202/232
IC3 Reset circuit type MAX701
C1, C4, C9,
C10, C11
100nF (same as 0.1uF)
C2, C3 22pF (15-30pF)
C5, C6,
C7, C8
1uF (if MAX232) or 0.1uF (if MAX202)
C12 4.7uF to 10uF depending on reset delay
R1 100 ohms
R2, R4, R5 1k ohms
R3 10k ohms
R6 10k ohms (Rev.B only)
XTAL1 What ever frequency you need (Chrystal or Resonator)
V1 5VDC/1A voltage regulator type TO220 with screw for proper cooling
LD1 LED for indicating ISP programming, normally 3mm RED
LD2, LD3 LEDs for general purpose 3mm, color is up to you
J1 Jumper 3*1 pins
J2,J3,J4 10pin IDC connector
J5 Connector 4*1 pins
J6 Jumper 2*1 pins (Rev.B only)
PB1 Reset push button
Q1 Brownout (Rev.B only) type Panasonic MN13811-S (O/C) or similar.

Demosoftware written in BASCOM-AVR is availible in zip format here (includes Basic source file and hex file). This simple program demonstrates how the on-board LED's can be turned on and off.

User feedback very much appreciated.
Simm100 is © Copyright 1997-2006 LAWICEL. All rights reserved.

                            ATmega163 & SIMM100
                            Author: rcinmo (Phil Moore) ( rcinmo@)
                            Date:   06-05-01 03:26

                            Just looking at the surface, I would think the mega163 would work in a SIMM100 board. Does it?

                         Re: ATmega163 & SIMM100
                            Author: Lars Wictorsson ( )
                            Date:   06-05-01 14:20


                            Yes it works well. We have customers using the Mega163 in SIMM100. The Mega163 is pin
                            compatible with the 8535, however by the time the SIMM100 was made 2 years ago, there was
                            no info on the Mega163, so the hardware I2C channel added onto the Mega163 isn't on the
                            "standard pins" of the SimmStick bus, but that is a minor change if you need to be compatible
                            with other simmstick peripherals.


Subject:         SIMM100 & Mega16 16MHz
   Date:         Fri, 10 May 2002 19:30:37 -0500
   From:        "Joe Cygan" <joe@

I just swapped the 8535-8 in my current project for my sparkling new Mega16-16MHz.  Works perfectly in the SIMM100!
Ohhh... what's this 24MHz crystal doing all alone, hmmm...... *evil grin*

Please Note ****  This board doesn't suit the 8515 type footprint. For this you will need the DT107 SimmStick. is the link to the PDF file for the MAX-701 Reset Circuit.
This URL may be subject to change in future.

Standard Brown Out Circuit details:

Dontronics Home Page

Copyright © 1996-2006 Dontronics
Top of Page