MiniMess

MiniMess (MiniMeas)
A cascadable measurement interface for pocket computers and -calculators
(or everything else that has a CMOS level UART).

Features:

• pocket calculator/computer enabled mini measurement thingy
• 10bit autoranging A/D converter (0-25V)
• 10bit D/A converter (3V3)
• cascadable
• fair precision
• "easy" to build (single sided layout)
• most complicated protocol, ever ;)
• Python, C (DLL) and Profilab applications available

Hardware

V2.0 schematic...

...and test layout

Here comes V2.0.
A much smaller version, compared to the old, milled V1.0 version.

The plug is now MiniFTDI compatible.

Circuit Description

Control Hard- and Firmware

(3/2011) JUST COPIED THIS FROM THE OLD PAGES.
A new firmware and software package is on its way...

Right now, only the GET_AD and SET_PWM functions are implemented.
To maintain compatibility with my old pocket calculators, the baud rate is fixed to 4800 bits/s.
Note: The 12F683 does not have an UART. The complete protocol is software coded ;)

The kids destroyed my docs. This was taken from the source.
Communication Master -> MiniMeas

  ;  CNAME   | CVAL |    CB    |    B0    |    B1    |    B2    |    B3
  ;----------+------+----------+----------+----------+----------+----------
  ; GET_AD   |  0   | 1AA00SXX | -------- | -------- | -------- | --------
  ; SET_PWM  |  1   | 1AA01DDD | 0DDDDDDD | -------- | -------- | --------
  ; GET_DATA |  2   | 1AA10NND | 0DDDDDDD | 0DDDDDDD | 0DDDDDDD | 0DDDDDDD
  ; SET_DATA |  3   | 1AA11NND | 0DDDDDDD | 0DDDDDDD | 0DDDDDDD | 0DDDDDDD
  ;
  ; A = address, S = sync, D = DATA, N = number of bytes, X = don't care
	
			

CB -> command byte
Bx -> data bytes

The address of the module (0-3) needs to be programmed into EEPROM address 0!
Use you PIC programmer for this...

If GET_AD was sent, the module answers with:

  ; 
  ; +--BYTE-1--+--BYTE-2--+
  ; | 1AARRDDD | 0DDDDDDD |
  ;
  ; AA = address; RR = range; D = data bits
			
			

The ranges are:

  ;    I:  0 -  2V     both FETs off (GPIO pins low)
  ;   II:  0 - 12V     FET1 on
  ;  III:  0 - 22V     FET2 on
  ;   IV:  0 - 32V     FET1 and FET2 on (GPIO pins high)
			
			

Some Useless Pics

an older, milled prototype...

config bits, if your programmer does not support them...

Download

MiniMess:

Includes:
- schematic (PDF)
- placement drawing (PDF)
- minimal BOM (TXT)
- layout, Eagle (BRD)

DOWNLOAD: MiniMess_hard_V20.zip Hardware, V2.0

MiniMess; additional, older stuff:

What a mess...
DOWNLOAD: firmware
DOWNLOAD: MiniMeas DLL
DOWNLOAD: example ProfiLab usage
DOWNLOAD: some python code (native or with DLL)

ASkr 03/2007: initial release V0.2
ASkr 03/2011: redesign; V2.0