Help to identify the 28-pin microcontroller!

[MicroCoder9]

28 pin microcontroller

Hi all,
I got an assignment to develop program for a 28-pin DIP type package microcontroller. The hardware is already designed and assembled but the microcontroller is damaged.

The number on microcontroller has been scraped off. Only info about microcontroller I could extract by tracing the PCB is as follows:

Pin 28 - Supply (+5V)
Pin 14 - Ground (supply -ve)
Pin 19 - Ground (supply -ve)
Pin 21 - Analog Input

Please can anyone help me identify the microcontroller!
Thanks in advance for any help.

 

[fenugrec]

how to identify microcontroller

Is there a crystal on the board? or is it an internal osc. ?
Is VDD=5 or 3.3 V ?
Does the board have an In-circuit programming socket?

Do you at least know what architecture it has / what brand?
You can try the parametric search on the microchip website,
if you think this could be a PIC.

Good luck
Christian

 

[MicroCoder9]

identify microcontroller

fenugrec wrote:

Is there a crystal on the board? or is it an internal osc. ?
Is VDD=5 or 3.3 V ?

There is no external crystal. VDD is 5 V.
The pinouts don't seem to match any of the PIC or AVR devices.

Any help in identification will be appreciated.

 

[fenugrec]

28 pin ucs

... What kind of assignment is this? Design a program for an unknown uC ?

CHristian

 

[MicroCoder9]

28pin 8051

The customer has a few faulty units in which all circuit seems to be OK except the microcontroller. In order to get them working again, he wants to replace the faulty micros by a new one. The company from where he purchased the instruments has closed down. So no support is available.
So I am trying to develop the program for the given hardware.

 

[antedeluvian]

pin 28 vdd pin 14 gnd microcontroller

I don't know what micro you have there, but you could make a Cypress PSoC fit. I am assuming that it is a 0.3" through hole device. The Cypress CY8C27443-24PXI has Vcc on 28 and ground on 14. Pin 19 can be left at ground and not used. It is possible to use pin 21 (P2_2 on this PSoC) as an analog input when the A/D converter is in location ASC23.

The PSoC consists of a micro and analog and logic blocks that can be shuffled around to suit your requirements, so you can place an A/D in the above location and enable the input to the A/D from the desired pin. It has an on-board oscillator and will operate at 5V. There are several possible devices that will fit in the same socket, the device I gave you is 16KBytes flash and 256 bytes RAM. You can get up to 32KBytes flash and 2Kbytes RAM

Depending on you experience, there may be quite a steep learning curve, but it is great fun to work with.

https://www.cypress.com/portal/serv...=215&gid=13&fid=24&category=All&showall=false

-Aubrey

 

[fenugrec]

psoc damaged program

Hmm, I didn't know Cypress made uC's ....
Anyway this chip looks a lot like what you're looking for. There can't be many DIP uCs that have VDD on 28, VSS on 14/19 and analog on the other pin... unless what you're working with is a cheap clone, in which case it will probably be code-compatible anyway!

Christian

 

[polymath]

Hi MicroCoder9

I find it strange that you have not posted a picture of the unit. This would help.
Who was the original manufacturer? You must know this as you state the company is nolonger in business. Tell us please.
The vagueness of you description will make many readers suspicious of your intentions.

I suggest you make a 28pin module board with a surface mount PIC on it.
If you select a suitable PIC then you can fit a ICSP/Debug connector on the module and make the code development quicker and easier.

Polymath

 

[MicroCoder9]

Hi antedeluvian
Thanks for the help. Yes, it is a 0.3" wide 28-pin DIP. The pinouts don't match any chip from Atmel, Microchip, Freescale, Philips or ST, and from the info you provided it seems to be a Cypress PSoC chip.

Hi polymath
Your suggestion about the 28-pin module board is a good idea, though my experience with PICs has not been very encouraging. The PIC16 instruction set has very limited capabilities as compared to 8051 or 68HC11. You have to use 3 or more instructions for many tasks which are possible with single instruction in other MCUs plus you have to keep switching banks to access various SFRs.

I fail to understand the reason about PIC's popularity when such other good architectures are available.

 

[rkodaira]

I fail to understand the reason about PIC's popularity when such other good architectures are available.

PICs have large availability and prices are reasonable
PICs have a lot of development boards and compilers (C, basic, pascal, jal)
PICs have free development software (MPLAB)
PICs have a lot of literature (books, projects in magazines, etc)
PICs have a lot of sites about them

All these factors are like honey to hobbysts and students, so the ring is closed

 

[fenugrec]

And I'm sure every electronics forum on the net has at least one PIC vs. AVR/8051/68HC thread, so there's no point in starting another war.

Christian

 

[Alan69]

The number on microcontroller has been scraped off. Only info about microcontroller I could extract by tracing the PCB is as follows:

Pin 28 - Supply (+5V)
Pin 14 - Ground (supply -ve)
Pin 19 - Ground (supply -ve)
Pin 21 - Analog Input

Please can anyone help me identify the microcontroller!
Thanks in advance for any help.

First, look at Eproms, with this pinout and no crystal this may not even be a microcontroller at all. You can do a lot of work with a properly programmed eprom, especially if you feed an output back to an input so the next location can change partly depending on what the last read value was.

After that, could also be about any controller if it is a mass market item. You can get chips wired about any way you want if you pay enough.. Or get a discount, ask them to sell you any factory errors where the pins were wired wrong.

Alan