Power supply – Digilent 240-071P User Manual
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PmodMAXSONAR™ Reference Manual
Serial data is sent from the PIC16F676 on the PmodMAXSONAR at 9600 baud, with 8 data bits, 1 stop bit, and no
parity bits. Received range data is formatted in a packet of 5 ASCII characters. The first character is an ASCII ‘R’,
followed by three ASCII characters representing the range, and terminated with a carriage return (ASCII value 13).
When the RX pin is high, serial data will be continuously sent on the TX pin as it becomes available.
Analog range data can be acquired from the AN pin of the PmodMAXSONAR. The scaling factor for the analog data
is (Vcc/512)V per inch. This gives approximate outputs of 9.8mV/in at an operating voltage of 5V, and 6.4mV/in at
an operating voltage of 3.3V.
Pulse-width output from the PmodMAXSONAR uses a scaling factor of 147µs per inch. After the 42 KHz pulses are
sent, the PW pin is set high. The PW pin is pulled low after the PmodMAXSONAR detects a target. The width of the
pulse will not exceed 37.5ms. If the pulse is 37.5ms long, no target has been detected.
Figure 2 shows an example of the timing of PWM pulses. The first pulse of 37.5ms indicates that no target has
been detected. The second pulse of 10ms indicates that an object has been identified 68 inches away from the
ultrasonic module.
Figure 2. Timing diagram for pulse-width output.
Table 1. Interface connector signal description.
Power Supply
Any external voltage applied to Vcc must be kept between 2.5V and 5.5V to avoid damaging the PmodMAXSONAR.
It is recommended to operate the board at 3.3V
Standard Pmod headers on Digilent boards provide both 3.3V and 5.0V power supplies for Pmods. Make sure that
the jumper next to the Pmod header is shorted correctly. Note that the voltage applied to Vcc will affect the
analog output level of the PmodMAXSONAR.
Note: For more information on the PmodMAXSONAR, see the MaxBotix LV-MaxSonar-EZ1 datasheet at
Pin
Example
Description
1
AN
Analog Output
2
RX
Range Control Signal
3
TX
UART Transmit
4
PW
Pulse Width Output
5
GND
Power Supply Ground
6
Vcc
Power Supply (3.3V/5V)
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