MCP2120-I/SLG Microchip Technology, MCP2120-I/SLG Datasheet - Page 5

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

2.0
The MCP2120 is a low cost infrared Encoder/Decoder.
The baud rate is user selectable to standard IrDA baud
rates between 9600 baud to 115.2 kbaud. The maxi-
mum baud rate is 312.5 kbaud.
2.1
Any time that the device is powered up, the Device
Reset Timer delay
any communication with the device is initiated. This is
from both the infrared transceiver side as well as the
controller UART interface.
2.2
The MCP2120 is forced into the reset state when the
RESET pin is in the low state. After the RESET pin is
brought to a high state, the Device Reset Timer occurs.
Once the DRT times out, normal operation occurs.
2.3
The device crystal is used to derive the communication
bit clock (BITCLK). There are 16 BITCLKs for each bit
time. The BITCLKs are used for the generation of the
Start bit and the eight data bits. The Stop bit uses the
BITCLK when the data is transmitted (not for recep-
tion).
This clock is a fixed frequency, and has minimal varia-
tion in frequency (specified by crystal manufacturer).
TABLE 2-1:
© 2007 Microchip Technology Inc.
Note 1:
BAUD2:BAUD0
2:
000
001
010
011
100
DEVICE OPERATION
Power-up
Device Reset
Bit Clock
An external clock is recommended for frequencies below 2 MHz.
For frequencies above 7.5 MHz, the TXIR pulse width
pulse width of 1.6 µs in the IrDA standard specification.
HARDWARE BAUD RATE SELECTION VS. FREQUENCY
0.6144
(parameter
1600
3200
4800
9600
800
(1)
32) must occur before
10417
15625
31250
2.000
2604
5208
3.6864
19200
28800
57600
4800
9600
Frequency (MHz)
4.9152
12800
25600
38400
78600
6400
2.4
The UART interface communicates with the "control-
ler". This interface is a Half duplex interface, meaning
that the system is either transmitting or receiving, but
not both at the same time.
2.4.1
The baud rate for the MCP2120 can be configured
either by the state of three hardware pins (BAUD2,
BAUD1, and BAUD0) or through software selection.
2.4.1.1
Three device pins are used to select the baud rate that
the MCP2120 will transmit and receive data. These
pins are called BAUD2, BAUD1, and BAUD0. There is
one pin state (device mode) where the application soft-
ware can specify the baud rate.
baud rate configurations.
(parameter
115200
7.3728
19200
38400
57600
9600
UART Interface
BAUD RATE
Hardware Selection
IR121) will be shorter than the minimum
14.7456
115200
230400
19200
38400
78600
(2)
20.000
104167
156250
312500
26042
52083
MCP2120
Table 2-1
(2)
DS21618B-page 5
F
F
F
F
F
Bit Rate
OSC
OSC
OSC
OSC
OSC
shows the
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