MCP2140A Microchip Technology, MCP2140A Datasheet - Page 16
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MCP2140A
Manufacturer Part Number
MCP2140A
Description
IrDA Standard Protocol Stack Controller With Fixed 9600 Baud Communication Rate
Manufacturer
Microchip Technology
Datasheet
1.MCP2140A.pdf
(60 pages)
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MCP2140A
2.10
The IR data rate of the MCP2140A is fixed at
9.6 kbaud. The actual throughput will be less due to
several factors. Many significant factors are under the
control of the developer. One factor beyond the control
of the designer is the overhead associated with the
IrDA standard.
Depending on the application, throughput may be an
issue in one or both directions.
2.10.1
Throughput is dependant on the direction that the data
is streaming and the characteristics of the Primary
Device and Secondary Device. Streaming throughput
from the Secondary Device may be different with
different Primary Devices. Also streaming throughput
from the Secondary Device may be different than
streaming throughput to the Secondary Device, with
the same Primary Device. Throughput examples are
shown in
actual observed data communications.
TABLE 2-4:
FIGURE 2-10:
DS22050A-page 16
PC
PIC IrDA Standard Stack
PIC IrDA Standard Stack
PDA (HP iPAQ hx2495b)
Note 1:
CTS
Note:
(6)
Primary Device
2:
3:
4:
5:
6:
7:
Buffers and Throughput
Table
Measured from Figure. (see comment)
Interpolated from Figure. (see comment)
10 bits transferred for each byte.
Using the PIC24 Explorer 16 Development Board with IR Transceiver Board
Using the MCP215X/40 Data Logger Demo Board and Board Firmware V1.4
IBM 600X Thinkpad (notebook computer) running Windows XP Professional (SP1)
MCP2140 Data Sheet, DS21790, Table 2-4, MCP2140 transmitted 240 bytes in this transmit time.
THROUGHPUT
IrDA throughput is based on many factors
associated with characteristics of the
Primary and Secondary devices. These
characteristics may cause your through-
put to be more or less than is shown in
Table
Receive Buffer Empty
MCP2140A Can Receive Data
2-4. These examples are based on
2-4.
THROUGHPUT EXAMPLES - 250 BYTES
HOST UART RECEIVE BUFFER AND CTS WAVEFORM
(4)
(4)
MCP2140A
MCP2140A
MCP2140A
MCP2140A
Secondary
MCP2140
Device
(5)
(5)
(5)
(5)
Receive Buffer Has 59 Bytes,
CTS Pin Driven High
Streaming
Direction
S -> P
S -> P
S -> P
P -> S
S -> P
Data
Receive Buffer
Full (60 Bytes)
Figure 2-11
sequence between a Primary Device and a Secondary
Device (MCP2140A). In this example after the “Primary
Device Sends Open Link Frame”, the time for the
Secondary Devices response is fixed by the operation
of the MCP2140A. After the “Primary Device Decodes
Secondary Device Response” the “Primary Device
Responds to Secondary Device”. Throughput may be
improved if the application program can be written so
that the Primary Device response as fast as possible.
Also when the “Secondary Device Sends Data”, the
frame should have the maximum number of data bytes.
Figure 2-12
Controller (and MCP2140A) streaming (transmitting)
250 bytes to a Primary Device (PIC24 + IrDA Standard
Stack Library).
Figure 2-13
(and Host Controller) receiving 250 streamed bytes
from a Primary Device (PIC24 + IrDA Standard Stack
Library).
Figure 2-14
Controller (and MCP2140A) streaming (transmitting)
250 bytes to a Primary Device (Notebook PC with IR
port).
Transmit Time
(3)
250 Byte
(ms)
650
354
337
549
332
(7)
(1)
shows the screen-capture of a MCP2140A
shows a second screen-capture of a Host
shows the screen-capture of a Host
shows an example communications
IR Data Packet Starts Transmission
Baud Rate
Receive Buffer Empty
MCP2140A Can Receive Data
IR Data Packet Transmitted
Effective
© 2007 Microchip Technology Inc.
7062
3692
7418
4553
7530
(2)
Comment
Figure 2-14
Note 7
Figure 2-12
Figure 2-13
Figure 2-15