MCP2120-I/SLG Microchip Technology, MCP2120-I/SLG Datasheet - Page 6

• Manufacturer Part Number: MCP2120-I/SLG
• Description: Infrared encoder/decoder, -40C to +85C, 14-SOIC 150mil, TUBE
• Manufacturer: Microchip Technology

MCP2120
2.4.1.2
When the BAUD2:BAUD0 pins are configured as ’111’
the MCP2120 defaults to a baud rate of F
To place the MCP2120 into Command Mode, the
MODE pin must be at a low level. When in this mode,
any data that is received by the MCP2120’s UART is
"echoed" back to the controller and no encoding/
decoding occurs. The echoed data will be skewed less
than 1 bit time (see
MODE pin goes high, the device is returned to Data
Mode where the encoder/decoder is in operation.
Table 2-2
ure the MCP2120’s baud rate.
The MCP2120 receives data bytes at the existing baud
rate. When the change baud rate command (0x11) is
received, the last valid baud rate value received
becomes the new baud rate. The new baud rate is
effective after the stop bit of the echoed data.
Figure 2-2
2.4.2
When the controller sends serial data to the MCP2120,
the baud rates are required to match.
There will be some jitter on the detection of the high to
low edge of the start bit. This jitter will affect the place-
ment of the encoded start bit. All subsequent bits will be
16 BITCLK times later.
TABLE 2-2:
DS21618B-page 6
Note 1:
Command
0x8B
0x87
0x85
0x83
0x81
2:
3:
4:
Hex
shows the software hex commands to config-
shows this sequence.
An external clock is recommended for frequencies below 2 MHz.
For frequencies above 7.3728 MHz, the TXIR pulse width
IrDA standard specification.
Command 0x11 is used to change to the new baud rate.
All other command codes are reserved for possible future use.
TRANSMITTING
(3, 4)
Software Selection
SOFTWARE BAUD RATE SELECTION VS. FREQUENCY
0.6144
1600
3200
4800
9600
800
parameter
(1)
10417
15625
31250
2.000
2604
5208
IR141). When the
OSC
3.6864
19200
28800
57600
4800
9600
/ 768.
Frequency (MHz)
4.9152
12800
25600
38400
78600
6400
2.4.3
When the controller receives serial data from the
MCP2120, the baud rates are required to match.
There will be some jitter on the detection of the high to
low edge of the start bit. This jitter will affect the place-
ment of the decoded Start bit. All subsequent bits will
be 16 BITCLK times later.
FIGURE 2-1:
Data Mode
When echoing the Data, once the first bit is
detected, it is echoed back. This means that
the echoed data is skewed no more than 1 bit
time.
The new baud rate can occur once the echoed
stop bit completes.
115200
7.3728
19200
38400
57600
9600
(parameter
RECEIVING
MODE pin goes low
Command Mode
14.7456
Controller sends baud
230400
115200
19200
38400
78600
IR121) will be shorter than the 1.6 µs
MCP2120 echoes baud
Controller sends 0x11
Data/Command Mode
Flow
(2)
© 2007 Microchip Technology Inc.
MCP2120 echoes 0x11
20.000
New baud rate
104167
156250
312500
26042
52083
MODE pin goes high
(2)
Data Mode
F
F
F
F
F
Bit Rate
OSC
OSC
OSC
OSC
OSC
/ 768
/ 384
/ 192
/ 128
/ 64