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Embedded Systems, Publishers

DonTronics - SIMM100

The Lawicel SIMM100



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.

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Last modified: February 24, 2024