MCP2120 Tutorial
Figure 3.19: Debug Flowchart - MCP2120 Developer鈥檚 Board #1 Side
Debug Board #1
Set up digital oscilloscope to
capture waveform on first
falling edge (Start bit)
Type character in PC #1
Hyperterminal window
Data
appear on
MCP2120
TX pin?
Yes
Data
appear on
MCP2120
TXIR pin?
Yes
Goto
Debug Board #2
No
Data
appear on
MAX232
R1IN pin?
No
No
Yes
Data
appear on
MAX232
R1OUT
pin?
Yes
Verify that the connection from
PC #1 to Board #1 is good.
Try communication with
another serial device
(such as PICSTART Plus).
No
Problem with MCP2120
Verify device has power/ground
Ensure jumper JP4 is open
Ensure crystal oscillator is correct
frequency and operating
Ensure Baud Rate is correct
(jumpers JP1, JP2, and JP3)
Try replacing with new MCP2120
Verify 3 pin header J4
is jumpered correctly
It appears that the
MAX232 device
is damaged
錚?/div>
2001 Microchip Technology Inc.
DS51246A-page 37
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