RS-232 Serial I/O Board

Downloads

Software / Firmware
Front page of article Download the accompanying software/firmware package for the RS-232 serial I/O board presented in Nuts & Volts magazine. Sample applications, documentation, firmware for the board, and software libraries for Windows and Linux are all included. This download package has been updated since the publication of the article to also include firmware for the Atmel AT90S4434 for those of you who would like to use that microcontroller for this project. You have your choice of file formats for the download package. Just about everyone is familiar with the .zip format, which can be uncompressed using WinZip or Windows built-in utilities. If you have the tar and gzip utilities, you may be interested in the .tar.gz format.


Here is firmware which has been modified to fix a problem with the analog-to-digital converters:

Schematic / PCB Layout
Due to space restrictions, the printed circuit board layout images were not printed in the Nuts & Volts article. These can be downloaded, along with the schematic, from the Nuts & Volts web site or from here:

Firmware for the Atmel AT90S4434

The original article in Nuts & Volts magazine utilized the Atmel AT90S8535 microcontroller in the project. However, a very similar microcontroller, the Atmel AT90S4434, can now also be used in this project. The '4434 is pin-compatible with the '8535 but has less memory. Since all of the memory on the '8535 was not used, the '4434 can be used in this project without sacrificing any features.

The slightly-modified firmware required for using the AT90S4434 is now included in the main download package above. Again, note that there are no other modifications necessary to use the '4434 besides using this version of the firmware.


Additional Boards - Updated 04/19/2001

The second batch of etched and drilled circuit boards has been ordered from the manufacturer. We have ordered enough for those of you who expressed interest up through April 16th. If you have missed out on this second batch and are interested in purchasing a board, let us know because we have ordered just a few extras. The cost of the boards from the second batch is $25.00 per board + a fixed $3.50 S&H regardless of the number of boards purchased.

Defective Boards

     -- View our original message regarding this issue.
We have learned that a couple of the boards we have already sent out were manufactured incorrectly by the board house. We have found that a couple traces may be shorted together on some of the boards. If a board contains a short, it could be anywhere -- we can't point you to the exact spot. If you locate a short, it will most likely be a hairline short. One way to deal with this is to run some current through it and blow it like a fuse. If you need some assistance or have questions, just contact us. For ideas on how to fix a bad board, view our original message regarding this issue. Note that we now test boards for this problem before they are shipped out.

Bill of Materials

     Below is a more detailed Bill of Materials than what appears in Nuts & Volts Magazine. It includes more part numbers for Digi-Key and Jameco.

Part

Component

Qty


Printed Circuit Board

1

C13, C14

27pF Ceramic Capacitor Digi-Key # BC1007CT-ND

2

C4 - C12

0.1uF Ceramic Capacitor Digi-Key # BC1133CT-ND

9

C1, C3

10uF Electrolytic or Tantalum Cap Jameco # 33689

2

C2

22uF Electrolytic or Tantalum Cap Jameco # 94094

1

R1, R8

1k ¼ watt resistor Jameco # 29663

2

R2 - R7

4.7k ¼ watt resistor Jameco # 31026

6

U2, U4

74LS245 Jameco # 47212

2

U7

Maxim MAX233 (Digi-Key # MAX233CPP-ND)

( Jameco # 106163)

1

U6

Maxim MAX708 (Digi-Key # MAX708CPA-ND)

1

U1

LM7805 Voltage Regulator, TO-220 Digikey # 296-1974-5-ND

1

Y1

8 MHz Crystal, parallel resonant (Digi-Key # X165-ND)

1

U3

Atmel '8535 microcontroller (Digi-Key # AT90S8535-8PC-ND)

OR

Atmel '4434 microcontroller (Digi-Key # AT90S4434-8PC-ND)

1

U5

MC14053 or equivalent (Digi-key # CD4053BCN-ND)

(Jameco # 13127)

1

J4

1x3 Header Jameco # 109575

1

J6 - J9

1x9 Header Jameco # 103392

3

JP1

2x3 Header Jameco # 115035

1

JP2

2x5 Header (Jameco # 67811)

1

J10

25-pin D-Sub, male (Jameco #15149)

1

J11

9-pin D-sub, female (Jameco # 104951)

1

J1, J3, J5, J8

Terminal Block: 3 pos, 3.5mm spacing, Weidmuller # 169968

(Digi-Key # 281-1401-ND)

11

D1, D2

LED Jameco # 152864

2


TO-220 Heatsink Jameco # 70771

1


Jumper/Shorting Block (Jameco # 22023)

3


8-pin Socket Jameco # 112205

3


16-pin Socket Jameco # 112221

1


20-pin Socket Jameco # 112248

3


40-pin Socket Jameco # 112310

1
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