BeagleBone Black connect to ultrasonic sensor Hcsr04

[claudiu claudiu.furca@yahoo.com]

I have currently tried to connect a ultrasonic sensor hcsr04 to my BBB with no success. 

The support material I was using is to establish the connection and execute a trigger to my sensor and read the output is: 

https://github.com/luigif/hcsr04.

When I`m executing the ./hcsr04 file I receive accordingly the being msg: >> Initializing PR >> Executing HCSR-04 code, which after it seems to wait for the signal to be triggered but never receives one.

Could you give me some advises? or if you experience working with this model of sensor and have some tips? 

[Dennis Meade]

What voltage are you using? For the HC-SR04 VCC should be 5V. 

[claudiu claudiu.furca@yahoo.com]

For the sensor's VCC im using the VDD_5V from BBB. 

On Wednesday, May 6, 2015, Dennis Meade <meade....@gmail.com> wrote:

What voltage are you using? For the HC-SR04 VCC should be 5V. 

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[doog]

On Thursday, May 7, 2015 at 1:44:57 AM UTC-7, claudiu <clip> wrote:

For the sensor's VCC im using the VDD_5V from BBB. 

and you do know that the BBB is a 3.3v device so level shifting is probable?

Doug 

[claudiu claudiu.furca@yahoo.com]

Well yes i do know that the BBB is a 3.3v with a 4-6 mA output. Therefore I have used the following configuration: 

* TRIGGER       P8_12 gpio1[12] GPIO44  out pulldown        Mode: 7 
* ECHO          P8_11 gpio1[13] GPIO45  in  pulldown        Mode: 7 *** with R 1KOhm
* GND           P9_1 or P9_2    GND
* VCC           P9_5 or P9_6    VDD_5V(from BBB)

but am I right ? 

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[evilwulfie]

unless you use a level translator you will blow up that gpio pin and or the whole processor

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[Chad Baker]

The sensor is expecting a 5V signal on the trigger input and generates a 5V signal on echo.
You are feeding a 3.3V signal from the BBB and accepting a 5V signal from the sensor.
Will the output of the BBB, 3.3V, be seen as a 5V input by the sensor?
Will the 5V signal from the sensor fry the gpio pin which is expecting a max voltage of 3.3V?
This is just looking at the voltages and not considering currents, dig out the spec sheets for the sensor to see what the voltage/currents are that it is expecting.
The MOSFET level shifters will transform the 3.3V to 5V and vice versa.
Transistors/resistors will do the same operation.
Chad

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[claudiu claudiu.furca@yahoo.com]

This is the sensor hcsr04 datasheet:

http://www.micropik.com/PDF/HCSR04.pdf

vol = 5V;

cur = 15mA;

As Chad said if I will attach a resistor between the the sensor echo and BBB will perform the level shift accordingly.Thus, as I previously mention I have attached a 1kohm resistor between the sensor pin echo and BBB so I could convert the voltage to the BBB expected 3.3V, as far as my calculations showed with a 1KOHM resistor. 

But will be the sensor satisfied  if I have plug it in the VDD_5V from the BBB? 

 

[Harvey White]

On Thu, 07 May 2015 11:45:01 -0500, you wrote:

>The sensor is expecting a 5V signal on the trigger input and generates a
>5V signal on echo.
>You are feeding a 3.3V signal from the BBB and accepting a 5V signal
>from the sensor.
>Will the output of the BBB, 3.3V, be seen as a 5V input by the sensor?

The cmos threshold is 75% of VCC, so 25% of 5 volts is 1.25 volts,
which gives a desired 1 threshold of 3.75 volts on the sensor.

Not likely to see the signal as a 1.

>Will the 5V signal from the sensor fry the gpio pin which is expecting a
>max voltage of 3.3V?

Yes. See the warnings in the manual.

>This is just looking at the voltages and not considering currents, dig
>out the spec sheets for the sensor to see what the voltage/currents are
>that it is expecting.

>The MOSFET level shifters will transform the 3.3V to 5V and vice versa.
>Transistors/resistors will do the same operation.

TI (and others) make unidirectional (can be switched for direction)
level translators that protect both sides of the load and translate
logic levels. The part number (typical) is something on the order of
74LVC8T245, IIRC. I'd recommend them highly. There are DIP packages
more suitable for breadboards.

Transistors can work, as can resistors, but the packaged device is a
neater solution.

Harvey

>Chad
>
>
>On 5/7/15 10:45 AM, claudiu claudi...@yahoo.com wrote:
>> Well yes i do know that the BBB is a 3.3v with a 4-6 mA output.
>> Therefore I have used the following configuration:
>> |* TRIGGER P8_12 gpio1[12] GPIO44 out pulldown Mode: 7
>> * ECHO P8_11 gpio1[13] GPIO45 in pulldown Mode: 7 *** with R 1KOhm
>> * GND P9_1 or P9_2 GND
>> * VCC P9_5 or P9_6 VDD_5V(from BBB)
>> |
>> |but am I right ? |
>>
>> On 7 May 2015 at 16:23, doog <doug....@gmail.com

>> <mailto:doug....@gmail.com>> wrote:
>>
>>
>> On Thursday, May 7, 2015 at 1:44:57 AM UTC-7, claudiu <clip> wrote:
>>
>> For the sensor's VCC im using the VDD_5V from BBB.
>>
>>
>> and you do know that the BBB is a 3.3v device so level shifting is
>> probable?
>>
>> Doug
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[Chad Baker]

I don't think that I said that.
I gave you some thinking material to think about.
But I did miss saying "transistor/resistor circuit", the circuit disappeared between the brain and the fingers.
Chad

[Karteek YV]

I've tried derek's example and it worked perfect
https://github.com/derekmolloy/exploringBB/tree/master/chp13/ultrasonic

[seniord...@gmail.com]

Hi, did you ever figure out the problem? I'm also using luigif's example and I have the same problem where the code just waits for an interrupt and never receives it....

[senthilv...@gmail.com]

Hi, even I was facing the same issue wherein my code was waiting for the interrupt, then when I started to debug the hardware connections, I found that I had interchanged the connections for echo & trigger pins, so after rectifying the connections, the code works fine and I am getting the distance output prints.