Date:   Thu, 20 Nov 1997 20:19:48 -0400
From: Antti Lukats antti@sistudio.com
To: atmel@pic.co.za
Subject: Re: AT89S8252

Don McKenzie wrote:
> 
> Has anyone fitted an AT89S8252 into a DT103 Simmstick yet?
> I know you were talking about this workhorse's advantages Antti, but
> can't remember if you did it in a 103 or not.

YES, I did. Works like magic. In the matter of fact I even ported
the old-famous Tiny-Basic 51 to 8252 using the internal EEPROM.
just in case anyone interested ready to burn hex file and also
full sources are now uploaded and available:

ftp://sistudio.com/pub/atmel/tb8252.zip
                  

1 by 780L5 +5 Voltage regulator in TO-92 case. (Optional)

1 by Capacitor C1 15pf to 30pf Ceramic (Install only if Crystal is installed)
1 by Capacitor C2 15pf to 30pf Ceramic (Install only if Crystal is installed)
1 by Capacitor C3 .01uf (or .1uf) Ceramic
1 by Capacitor C4 .01uf (or .1uf) Ceramic

For AVR devices:
At the time of writing, the capacitor values either side of the crystal
are yet to be determined, as no value is specified in the data sheets.

PWMVDD: Currently not used. (Could be used for LCD Brightness)
1 by Capacitor C5 4.7uf Electrolytic (PCB mount.) or Tant. @16 V.
1 by Resistor  R17 10K .25 watt.
1 by Resistor  R19 10K .25 watt.
1 by Resistor  R21 33K .25 watt.

PWMVPP: Used for programmer mode.
1 by Capacitor C6 4.7uf Electrolytic (PCB mount.) or Tant. @16 V.
1 by Resistor  R14 10K .25 watt.
1 by Resistor  R15 10K .25 watt.
1 by Resistor  R16 10K .25 watt.
1 by Resistor  R18 10K .25 watt.
1 by Resistor  R20 10K .25 watt.
1 by Resistor  R22 33K .25 watt.
1 by Resistor  R23 1K  .25 watt. ;R23 and R24 are used for...
1 by Resistor  R24 3K9 .25 watt. ;Op-Amp voltage divider.
1 by NPN Transistor Q2 BC548
1 by NPN Transistor Q3 BC548
1 by LM324 Op-Amp I.C.

VDDON: Used for programmer mode.
1 by Resistor  R11 10K .25 watt.
1 by Resistor  R12  1K .25 watt.
1 by Resistor  R13 10K .25 watt.
1 by NPN Transistor Q1 BC558
       
Header J8:
Brings out PWM2, PWM1, and Ground, all on one set of pins.

Non-AVR Power up reset:
1 by Capacitor C7 4.7uf Electrolytic (PCB mount.) or Tant. @16 V.
1 by Resistor  R1 10K .25 watt.

AVR Power up reset:
1 by Capacitor C8 4.7uf Electrolytic (PCB mount.) or Tant. @16 V.
1 by Resistor  R2 10K .25 watt.

Header J1:
Selects power up reset between non-AVR and AVR.
Default set to non-AVR, as this board is designed as a programmer
using an AT89C51 or AT89C52.
For AVR, cut the track on the component side of the board between pin 1 and
2 of J1 and connect pin 2 to pin 3. This can be done with a 3 pin male
header connector and selected with a test link.

Headers J2 and J3:
These select between the board being a programmer board or a target board.
The default settings are for use as a programmer. As above, you could use
headers and links to change these settings.
1 by Resistor  R25 100 .25 watt.
R25 is used to limit current for the VPP supply voltage.

EEPROMs E3 and E4:
Provision is made to fit both SPI and IIC type EEPROMs.
Resistors R4 and R5 (both 10K) should be fitted for E3 installation.

SPI Bus:
Contains all the signals required for In-Circuit-Programming.

LCD Bus:
The LCD header pins suit both the 14 and 16 pin types.
On units that have two controllers, pin 15 is used as a chip select.
This allows you to control 4 by 40 standard displays.
R3 (330) supplies a limited +5V to the bus.
J7 selects between a 10K pot and PWMVDD for contrast control.

AUX Header:
This picks up on all the signals that the SimmStick bus misses out on.

Bells and Whistles:
1) Make a noise.
2) Flash a few LEDs.
3) Press some buttons.
The Piezo buzzer can be used for noise making.
LED1 and LED2 plus R9 (560) and R10 (560) can report all sorts of
adventures, while SW1, SW2, with R6 (330), and R7 (330) giving two
input signal toggles. J6 and R8 will allow permanent link settings for
power up or other control vectors.

There is currently no software available to run this device as a programmer,
but there should be in the future.

Circuit diagram for DT102