Electronics TSP - 3 Manual De Instrucciones página 14

digital output is made at the µMaxµm ® data output connector at pin # 5 (SMOD). For BCD data communications
the SMOD pin is left unconnected and for ASCII communication the SMOD pin is connected to pin # 3 (GND).
Internally the SMOD pin is tied to Vcc with a pull-up resistor.
CLOCKED BCD DATA COMMUNICATION TRANSFER
THEORY OF OPERATION:
Enabling the data request line (SREQ\, pin # 4) will activate data transmission. The SREQ\ is active low, it
must go from high to low and held low until data transmission starts then it can be brought high. A single
output data reading comprises 13 digits (d1 - d13) with each digit being 4 bits long for a total of 52 bits for
each message. The bit order for each BCD digit is LSB to MSB. Data is valid during the low clock pulse and
during either clock transition (from low/high or high/low). The data transmission is terminated at the end of
each reading. One display value is transmitted for each SREQ\ received.
BCD DATA FORMAT:
b0 b1 b2 b3 b0 b1 b2 b3
d1 d2
ALL "F"
7th digit on inch
mode otherwise
its "F"
When mm units are selected the format is as shown with d6 through d11 representing the 6 digits on the LCD
display. When inch units are selected a 7th digit may be displayed for user-entered presets. If this high order digit is
inactive the format is as shown in the table above. On the other hand if the 7th digit is active the d4 position will be
used to contain the BCD equivalent of its value.
IM0060_sp
----------------------------
d3 d4 d5 d6 d7
MSD
SIGN
0: = +
8: = -
DECIMAL POINT
X . X . X . X . X . X .
5 4 3 2 1
b0 b1 b2 b3 b0 b1 b2 b3
d8 d9 d10 d11 d12
LSD
MEASUREMENTS
0
d13
UNITS
0: = mm
1: = inch
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