User manual

MCP3421 Weight Scale Demo Board User’s Guide
DS51918A-page 18  2010 Microchip Technology Inc.
A.2 BOARD – SCHEMATIC
R24
523
+5V
R25
4.7K
V
DD
LCD1
LCD_2X16_COG
+5V
MCP1702
RD2
RD1
RD0
DB0
DB1
DB2
DB3
DB4 DB5
DB6
DB7
E
R/W
RS
V
EE
Vcc
GND GND1
3
2
1
14
13
12
15
11
10
9
8
7
5
4
6
4550_RA0
4550_RA1
4550_RA2
4550_RA3
VOUT
U4
V
IN
GND
D5
1N914
2
3
1
C7
0.1
UF
P
OWER ON
D6
R19
1.5K
BAT1
9V
9V DC Battery
* SEE NOTE 1 BELOW
C6
0.33uF
2
3 1
9V
J1
9V AC Power Supply
* Note 1: Use 9V power supply or 9V battery, but not both at the same time.
J18
1
2
+5V_A
EXCITATION
LC1
LOAD
CELL
LC2
LOAD
CELL
INPUT –
J4
J19
1
2
OUTPUT
INPUT +
J5
R38
1k
Extra Gain Lo
J9
R37
220
J8
Extra Gain Hi
R31 220
PGA
J10
C10
10nF
C18
1uF
C17
10nF
R35
220
MCP6V07
R30
2.2K
Extra Gain
J11
Extra Gain
J12
PGA
J13
1K
R39
1K
R36
10K
R17
+5V
C70
47uF
L5
10uH
10uH
L6
C69
47uF
D11
R27
1.5K
+5V
Reset
PIC18F4550
U2
44 Pin TQFP
20 MHz
X1
D12
D13
R32
R33
R34
1.5K 1.5K
1.5K
+5V
+5V
+5V
R21
24.9 R22
24.9
Pin 3 Pin 2
C4
0.1uF
D14
C11
0.1uF
C12 0.1uF
U5
R29
2.2K
47K
R28
R26
47K
C19
1uF
C20
1uF
MCP3421 A0
R18
10K
+5V +5V +5V
D7
D8
D9
RB0
RB1
RB2
S2 S3
S4
1.5K
1.5K
1.5K
R13
R14
R15
SSL–LX15IC
D3
R20
332
C8
C14
10uF
10uF
C13
0.1uF
L1
10uH
None
R23
C15
18pF
GND GND
C16
18pF
C9
0.1uF
J_MINI_USB_HRS_UX60_MBM5ST
USB1
MINI USB
NC
NC
RB4/CSSPP
RB6
RB7
MCLR
RA1
RA2
RB5
RA3
RA0
RC6
RC5/D+
RC4/D–
RD3/SPP3
RD2/SPP2
RD1/SPP1
RD0/SPP0
VUSB
RC2
RC1
NC
RC7
RD4/SPP4 RD5/SPP5 RD6/SPP6 RD7/SPP7
V
SS
VDD RB0 RB1 RB2 RB3
NC
RC0
OSC2
OSC1
V
DD
VSS
RE2/OESPP
RE1/CK2SPP
RE0/CK1SPP
RA5
RA4