Specifications

Chapter 3 – Input/Output Interfaces
66 PL 3120/PL 3150/PL 3170 Power Line Smart Transceiver Data Boo
k
Data are recognized in the IATA format as a series of 6-bit characters plus an even parity bit per character. The process
begins when the start sentinel (hex 05) is recognized, and continues until the end sentinel (0x0F) is recognized. No more
than 79 characters, including the 2 sentinels and the LRC character, will be read. The data is stored as right-justified
bytes in the buffer space pointed to by the buffer pointer argument in the io_in() function with the parity stripped,
and includes the start and end sentinels. This buffer should be 78 bytes long.
The magtrack1 input object optionally uses one of the I/O pins IO0 – IO7 as a timeout/abort pin. Use of this feature is
suggested because the io_in() function will update the watchdog timer during clock wait states, and could
result in a lockup if the card were to stop moving in the middle of the transfer process. If a logic 1 level is
detected on the I/O timeout pin, the io_in() function will abort. This input can be a oneshot timer counter
output, an R/C circuit, or a DATA_VALID~ signal from the card reader.
A PL Smart Transceiver with a clock rate of 10MHz can process an incoming bit rate of up to 7246 bits/second when
the strobe signal has a 1/3 duty cycle (t
high
= 46µs, t
low
= 92µs). At a bit density of 210 bits/inch, this translates to a
card speed of 34.5 inches/second. The bit rate processing capability scales with PL Smart Transceiver input clock
rate.
Magcard Bitstream Input
A magcard_bitstream I/O object provides the ability to read unprocessed serial data streams from most magnetic stripe
card readers in real time. This function can be used to read magnetic card data in either direction, forward or reverse,
because the data does not need to follow any specific format.
This I/O object can read up to 65,535 bits of data, stored in 8192 bytes of data, from a magnetic stripe card reader.
Serial Data
Clock
IO10
IO9
IO8
IO0
IO1
IO2
IO3
IO4
IO5
IO6
IO7
Timeout
IO11
Figure 3.27 Magcard Bitstream Input
Neurowire Input/Output Object
The Neurowire object implements a full-duplex synchronous transfer of data to some peripheral device. It can operate as
the master (drive a clock out) or as the slave (accept a clock in). In both master and slave modes, up to 255 bits of data
can be transferred at a time. The Neurowire I/O suspends application processing until the operation is completed. The
Neurowire object is useful for external devices, such as A/D, D/A converters, and display drivers incorporating serial
interfaces that conform with Motorola’s SPI or National Semiconductor MICROWIRE
TM
interface.