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This project comes as a KIT.
It includes these components:
- Low-cost
DMM (digital multimeter) M830D
- TX
(transmitter) circuit and
wireless module TX-433. These are mounted within the DMM housing.
- RX
(receiving) circuit with a
wireless module RX-433, LCD and piezo buzzer.
The general idea is to read all
LCD data from a cheap DMM (directly from its main chip.) This data is sent
and received by wireless modules, read by the RX circuit and then displayed again.
Sounds pretty easy, not?
Here are the
technical specifications:
- Low power operation (8-10 mA
@9V) with PIC
18F452 (TX) and 18F2550 (RX) microcontrollers running at 4 MhZ.
- Sampling rate: around 3
samples/sec.
- Max. distance between the RX
and TX circuits: 30m indoors and 100m outdoors.
- Software is 100% upgradable with a simple bootloader.
- Low power LED blinks when
sending / receiving data.
- TX circuit: PCB Dimensions:
30 x 31 mm or 1"18 x 1"22, weight: 8 grams.
- RX circuit: LCD contrast
adjustable by user.
- RX circuit: PCB Dimensions: 40 x 41 mm or 1"57 x 1"61, weight: 10 grams.
Hex files available.
Last update: June 1, 2006.
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Main Connections:
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RX
circuit diagram (top view) |
Header pinouts * |
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| JP1 |
Nokia
3310 LCD |
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JP2 |
RS232
interface |
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JP3 |
RX
module, supply, I/O |
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1 |
VDD, +5V |
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4 |
TX |
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1 |
+9V
input from battery |
| 2 |
SCLK |
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3 |
GND |
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2 |
input
from RX-433 module |
| 3 |
SDA |
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2 |
RX |
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3 |
NC (no
connect.) |
| 4 |
D/C |
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1 |
+5V |
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4 |
GND (to
battery and RX-433) |
| 5 |
CS |
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5 |
LCD
contrast adjust input |
| 6 |
GND |
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6 |
+5V output
(to RX-433) |
| 7 |
Vout |
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| 8 |
RES |
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* Note: pin 1
is marked by a red arrow in the
diagram |
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TX
circuit diagram (top view) |
Header pinouts * |
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| JP1 |
to TX-433
module |
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JP2 |
RS232 |
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JP3 |
LCD inputs |
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JP5 |
LCD inputs |
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1 |
+V |
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1 |
+V |
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1 |
+V |
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8 |
A2 |
| 2 |
TX_out |
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2 |
RX |
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2 |
G2 |
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7 |
B2 |
| 3 |
GND |
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3 |
GND |
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3 |
C3 |
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6 |
C2 |
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4 |
TX |
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4 |
A3 |
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5 |
D2 |
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5 |
G3 |
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4 |
E1 |
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6 |
COM (GND) |
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3 |
G1 |
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7 |
NC, no connect. |
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2 |
F1 |
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8 |
BP, backpane |
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1 |
A1 |
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| JP6 |
LCD inputs |
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JP7 |
LCD inputs |
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JP8 |
LCD inputs |
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| 8 |
Buzzer in |
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1 |
B1 |
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1 |
B3 |
| 7 |
Lobat in |
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2 |
C1 |
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2 |
D3 |
| 6 |
dp1 |
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3 |
D1 |
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3 |
E2 |
| 5 |
dp2 |
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4 |
F2 |
| 4 |
POL |
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| 3 |
AB4 |
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| 2 |
E3 |
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1 |
F3 |
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* Note: pin 1 is
marked by a red arrow in the diagram |
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DMM LCD connections |
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DMM M830D chip pictures |
DMM M830D chip
pinout (top view) |
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RS232 interface: JP2 provides the interface to connect to your COM
port and hyper terminal. Also used for bootloading (module software update.)
Check under the download section below for the latest version. Bootloading of
the HEX-file can
be done with
Tiny Bootloader.
RX circuit, LCD contrast Adjust: Connect pin 5, JP3 to +5V before powering up.
Release when the desired the contrast is reached.
Downloads:
right-click & save as
Info & datasheet:
Screenshots:
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TX circuit (top view) |
RX circuit (top view) |
DMM (back cover removed) |
RX circuit (working) |
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| WMM KIT 1 contents: picture |
WMM KIT 1 contents:
description |
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- DMM M830D
- Nokia 3310 LCD
- RX circuit
- RX-433 module
- SIL contacts
- Piezo buzzer
- 9V battery clip
- TX circuit
- TX-433 module
- Flatcable
Blue= TX (DMM, TX circuit and module)
Black= RX (RX circuit and module, LCD, Buzzer) |
Tools:
Check out our development
tools
page.
The PIC code was made with the PCWH
CCS
compiler ($425,-); you can install Microchip's
MPLAB IDE (click on the link and you can get it for free) with it to get things
running smoothly.
Bootloading of the modules is done
with the excellent
Tiny PIC bootloader, through RS232 (JP2).
Eagle 4.11e
was used for the schematic & PCB layout.
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