DT107 40 pin Atmel Micro on a SimmStick

The DT107 board replaces the DT103 and suits both the old and new (AVR) Atmel 28 and 40 pin Micros, and is based on the SimmStick Platform.

Features

  • 28, and 40 pin footprints to suit Atmel AVR and Non-AVR Micros.
  • The 40 pin footprint suits the AVR 8515 and the older 40 pin 8051 type chips including the 8252.
  • Optional Brown Out / Reset Circuit
  • RS-232/Header with provision for swapping ports to the real UART.
  • RS-485/RJ-45  with provision for swapping ports  to the real UART.
  • Kanda programming header
  • 78L05 Regulator
  • Reset inversion circuit
  • On board test LED
  • SPI Serial Eeprom. AT25256
  • Provision for Crystal (and Caps), or Resonator Oscillator.
  • A 40 pin header (40 pin Micro reversed) at the top edge of the board.
  • Support for the BasicX-01 chip and EEPROM.  (http://basicx.com)
  • Support for BasicX Ram Sandwich at J3.  (http://basicx.com)
  • Support for an Emulator pod at J3.
  • Signal connection via the 30 pin edge connector, or 30 pin male straight or right angle header, as well as 40 pin header.
  • Fully SimmStick(tm) compatible. See: SimmStick Definition
  • Mates with the the DT006 Little "rAVeR!" Programmer. 
  • Replaces the now obsolete DT103 Board.

  Click on the Icons for Schematics in PDF or GIF format.

 

Assembly Instructions

You can change Micro types if you install a 28 pin socket in the U6 position, and two 20 pin machine pin strips into the U1 position.

Parts List

1x DT107 SimmStickTM PCB

1 x 78L05 VR1  TO-92 +5 Regulator in  case.

1 x Cap C7  .01uf (or .1uf) Ceramic
1 x Cap C8  .01uf (or .1uf) Ceramic
1 x Cap C9  10uf Tantalum or Electro.
1 x Cap C10 4.7uf-10uf Electrolytic or Tant. 16V
1 x Cap C11 .01uf (or .1uf) Ceramic
1 x Cap C12 .01uf (or .1uf) Ceramic
1 x Cap C13 .01uf (or .1uf) Ceramic
1 x Cap C14 .01uf (or .1uf) Ceramic
1 x Res  R1 10K  (Used for power up-reset circuit.)
1 x Res  R2 10K  (Res pullup & part of power-up reset)
1 x Res  R3 10K  (Install only for non-AVR.)
1 x Res  R4 10K  (Install only for non-AVR.)
1 x Res  R5 100K (CS Serial EEPROM Pull-up)
1 x Res  R6 2.2K (RS-485 Pull-down)
1 x Res  R7 100  (RS-485 Network Termination resistor)

1x PNP small signal transistor. Q1 BC558 (Only for non-AVR)

US Type 2N4403 can be used, however it must be rotated 180 degrees so that the flat side of the transistor is facing away from U5 and not towards it as shown on the overlay.

Crystal or Resonator

And either a Crystal of a suitable value, or a 3 pin Resonator. If a crystal is fitted then C5 and C6 must be installed. If you use a Resonator, then you mustn't install these two caps.

X1 Crystal/ Resonator to match your clock requirements
1 x Cap C5  15pf to 22pf Ceramic (only with Crystal)
1 x Cap C6  15pf to 22pf Ceramic (only with Crystal)
Optional RS-232 Serial Communications:
1 x Cap C1 1uf Electrolytic (PCB mount.) or Tant. @16 V.
1 x Cap C2 1uf Electrolytic (PCB mount.) or Tant. @16 V.
1 x Cap C3 1uf Electrolytic (PCB mount.) or Tant. @16 V.
1 x Cap C4 1uf Electrolytic (PCB mount.) or Tant. @16 V.
1 x MAX-232 U2 (or equivalent)

It may also pay to install a 16 pin socket for the Max-232, as you may have to remove it for some configurations.

Optional RS-485 Serial Communications:
    1x MAX-485 U4 (or equivalent)

Optional SPI Serial EEPROM
   1x AT25256 U3

Brown-Out Circuit:

This small IC (U5) in a TO-92 package is used to stop the Micro operation becoming unpredictable during a power 'brown-out'. In most cases this isn't required. It's just an added precaution for reliable operation. The older Atmel micros may well need this device.

By just simply ignoring the brown-out circuit and installing resistors R1 and R2, the circuit operation should be fine.

R1, and R2 must be installed at all times for normal operation. 
Yes, even if you don't use a brown-out circuit.

If you wish to use the brown-out circuit, it's just added to the board, and can be either a CMOS or Open Collector type.

You can use the following I.C.'s:

  • Panasonic MN13811-S (Open Collector)
  • Panasonic MN1381-S (CMOS)
  • Zetek ZM33064
  • Motorola MC33064/P

Other types may also be suitable. These should switch at between 4.2 and 4.6Volts. This is for +5 Volt operation.

Status LED One (Optional)
LED1  1 x 3mm LED.
R9    1 x Res  1K

Kanda Compatible Connector (Optional)
J4    10 pin IDC Connector. (2 x 5 male header).
LED2  1 x 3mm LED.
R8    1 x Res  1K

AVCC: (Used for A/D 28 pin Micros) (Optional)
C15   1 x Cap .1uf (100nf) Ceramic
R10   1 x Res 100

Resistor Network RP1 for Non AVR
    9 x 10K Resistors, 10 pin device.
    Connects pins 31 to 39 of the micro to VCC 
   via 10K Pull-ups.

We figure on using a 10 pin resistor network and installing it in a SIL socket if you want to use non-avr then avr on the same board. We have allowed for pin 31 in this network. See schematic.

Pin 31 needs the option to be pulled high for the AT89S8252.
Pin 31, EA / VPP, needs option to be tied to vcc for internal program execution.

Headers

JP1:
Header block for unused gates of the MAX-232. These are spares, but can be useable if jumpered correctly for other handshaking RS-232 lines.

JP2:
Used to Isolate the +5V signal on the edge connector from the 78L05 regulator output if it is installed. Both outputs should never be used together. A test link and two male posts are used to reinstall the regulator output. Default open.

JP3:
Used to connect, or swap RS-232 and RS-485 connections to the Micro.
This may be be understood in conjunction with a schematic in front of you.

  • "A" Comms is the section that deals with RS-232 signals.
  • "B" Comms is the section that deals with RS-485 signals.

To connect the hardware UART of the micro to the SI and SO signals,  you need to connect J3 pin 3 to pin 5, and pin 4 to pin 6. This also connects these signals to the on board MAX-232 if installed. This is basically how most other SimmSticks are set.

To connect a "Software bit-banged" UART of the micro to the RS-485 circuitry, you need to connect J3 pin 7 to pin 9, and pin 8 to pin 10.

To connect the hardware UART of the micro to the RS-485 circuitry,  you need to connect J3 pin 1 to pin 3, and pin 2 to pin 4.

To connect a "Software bit-banged" UART of the micro to the MAX-232, you need to connect J3 pin 5 to pin 7, and pin 6 to pin 8.

JP4:
Connect pin 1 to pin 2 for AVR operation, and pin 2 to pin 3 for Non-AVR operation. This uses Q1 to invert the reset signals to match the Simm Bus.

JP5:
Used to terminate the RS-485 Network. Default open.

J1:
SimmStick Bus.

J2:
RJ-45 Connector for RS-485 Comms.

J3:
 40 pin header, pin for pin layout reverse compatible with 40 pin Micro.
Also used for Ram Sandwich.

Emulator:?
If a 40 pin header is used in position J3, then the setup can be used as an emulator. But watch out for pin crossover. If you crimp a 40 wire cable with a .6" DIP connector one end, and a .1"x 2 rows of 20 pins IDC type connector the other, you will find that the 40 pin male header (J3) on the DT107 board is the correct way around.

The pinout doesn't correspond to the Micro pinout as there must be a crossover. This happens in 99% of cases.

J4:
Kanda Programming header.

J5:
1 x 3 pin header. 1 test Link. Configure AREF to VCC for 28 pin micro.

Comments and Corrections welcome!

5-Nov-2000 Brian Millier wrote:

Hi Don:  I got the parts needed to finish the DT107 and tried it > out with the BasicX. No luck- dead as a nit on the simple "hello world" program. I tracked the problem down to the fact that there was no connection between the serial EEPROM pin 2 and the 8515 pin 7. When I wired that up, things worked OK. Luckily you had sent me 2 PCBs so I was able to track down the offending trace on the unpopulated board. It turns out that both my boards share the same problem. If you follow the trace outlined above, it leads to a via that is between R5 and R6. It is the second via up from the SIMM bus, ( if you just count the vias actually between the two resistors.) These vias are awfully small so I hope that this will not be a fabrication problem for the PCB company.

While I did not extensively test the RAM sandwich functionality, I did put a RAM write loop into the program, and it passed through that OK. ( program dies if the RAM sandwich is not present or working). Thought I'd better let you know about this quickly, in case this flaw is present in all boards.
regards
Brian Millier
Technical Manager
Chemistry Department
Dalhousie University
Halifax, N.S. B3H 4J3

Hi Brian.
We had to reduce the via pads and hole sizes just to get the board to route. My board man "Mick" pulled his hair out over this one.
see: http://www.dontronics.com/graphics/mik2.jpg I just checked 10 random boards and they are all OK, but of course no guarantee. It was the physical plated through on that via hole then was it?

OK, I just checked many more, but I'll add a little note. Not everyone will fit a basicx or ram sandwich, but if they do and it doesn't work, this will assist a lot. And they may well want to fit the serial EEProm anyway.

Cheers Don...