SRF04 Просмотр технического описания (PDF) - Unspecified

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SRF04

Ultra-Sonic Ranger

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SRF04 Technical Documentation

10/22/12 5:35 AM

There is more information in the sonar faq.

Update - May 2003

Since the original design of the SRF04 was published, there have been incremental improvements to improve

performance and manufacturing reliability. The op-amp is now an LMC6032 and the comparator is an

LP311. The 10uF capacitor is now 22uF and a few resistor values have been tweaked. These changes have

happened over a period of time.

All SRF04's manufactured after May 2003 have new software implementing an optional timing control input

using the "do not connect" pin. This connection is the PIC's Vpp line used to program the chip after

assembly. After programming its just an unused input with a pull-up resistor. When left unconnected the

SRF04 behaves exactly as it always has and is described above. When the "do not connect" pin is connected

to ground (0v), the timing is changed slightly to allow the SRF04 to work with the slower controllers such as

the Picaxe. The SRF04's "do not connect" pin now acts as a timing control. This pin is pulled high by

default and when left unconnected, the timing remains exactly as before. With the timing pin pulled low

(grounded) a 300uS delay is added between the end of the trigger pulse and transmitting the sonic burst.

Since the echo output is not raised until the burst is completed, there is no change to the range timing, but the

300uS delay gives the Picaxe time to sort out which pin to look at and start doing so. The new code has

shipped in all SRF04's since the end of April 2003. The new code is also useful when connecting the SRF04

to the slower Stamps such as the BS2. Although the SRF04 works with the BS2, the echo line needs to be

connected to the lower numbered input pins. This is because the Stamps take progressively longer to look at

the higher numbered pins and can miss the rising edge of the echo signal. In this case you can connect the "do

not connect" pin to ground and give it an extra 300uS to get there.

http://www.robot-electronics.co.uk/htm/srf04tech.htm

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