Hello everyone,
I’m trying to build a stand alone mower. It works except that in some places it should not go, hence the need for a perimeter wire.
I bought the perimeter wire and sensor generator kit.
Unfortunately, I have no detection of the sensor over the wire.
I noted that the sensor must be perpendicular to the wire for good detection.
I checked the location of the components, and the soldering (and I am not proud of it).
In the small Arduino program, I have a value for the sensors but they vary very little (about 850 on the analog input of an esp8266).
There is a divider bridge to have 3.3v on pin A0 of the esp.
( Generator board is powered at 12V and sensor board is powered at 5V)
I varied the potentiometer to resonate with the signal…no better.
Could you please guide me a bit to look in the right direction for what is wrong?
Hello and thank you for your reply.
Indeed, I did go through the tutorial several times, to see where I had gone wrong (it is this tutorial that made me buy the kit)
I didn’t go through all the calculations in the tutorial (very well done, very didactic), but I think I can trust the expertise of the person who wrote it for us… he outdid me.
For the little tinkerer that I am, placing components on a board, especially with the cardboard sheet provided with the kit, is quite simple.
On the gif, the sensor is at 10-15 cm and perpendicular to the cable. I tried closer and further, unfortunately I don’t have a big variation on the Arduino IDE console.
I’m around 850 for the value read by the esp, and I don’t vary more than +/-5 points from this value. I have the impression that it is the normal “noise” of my house that makes this value vary.
The cable I’m using for my tests is a 0.5mm2 cable, 1m long at most.
I can provide photos of the installation if needed to solve the problem.
If you have a lead, I’ll take it, as I’m a bit lost.
How are you powering the generator circuit? You have a possible range of voltages and the current needs to be sufficiently high. 12V, 3A should work well.
Good evening,
Yes, the power supply is 12V DC / 5A.
The + is in the center of the connector, the - on the periphery.
Shouldn’t I at least have a voltage on the perimeter cable with a simple voltmeter?
In Ac or DC on the multimeter I have nothing.
You’d need an oscilloscope as opposed to a voltmeter. The high and low would “cancel” to give effectively 0 on a multimeter.
How far away does the “sensor” need to be from the cable to reliably detect the signal? Not much else would affect the reading beyond the perimeter wire, so the robot would be programmed accordingly, even if the signal is not too strong.
If the perimeter wire is actually working, the sensor only detects you noise then. With or without the perimeter wire I have values that hardly move, only a few units, not even a dozen, see a hundred as in the tutorial gif.
In short, I had to do something wrong I can’t find my mistake.
I thank you for your help. Have a nice evening.
It looks like you have all of the components in the correct locations (roughly speaking without looking into details).
Note that hot glue is electrically conductive (if that’s what you used).
It also looks like the end of the power supply was customized? Did you ensure proper connections and center positive?
Did you vary the potentiometer?
What code are you using?
Hello
And thank you for coming back to this topic.
“It looks like you have all of the components in the correct locations (roughly speaking without looking into details).”
Yes, indeed, all the components are in the right place. I’ve been able to verify this several times.
“Note that hot glue is electrically conductive”
I did indeed use hot glue to hold the connectors…oops! I removed the glue.
“It also looks like the end of the power supply was customized? Did you ensure proper connections and center positive?”
You are right, the power supply comes from another hardware (my old firewall server), the voltage and current are correct for this use (12v - 5A DC). The connector has been changed because it is not adapted, the plus is well in the centre, and the minus in the periphery. The output voltage is correct. I will try to find another power supply. But this power supply has served me before on my robot when I was building it before I had the battery. I checked the soldering of the connector as well, I pulled on it a bit, it is strong.
“Did you vary the potentiometer?” yes, in both directions until the little “click” indicating the end of the potentiometer’s travel.
“What code are you using?” I used the analog readout example in the Arduino IDE, I adapted it for an esp8266 (easier to test than carrying around the Arduino mega), in short no more than 20 lines of code, I will post it at the end of the day.
“Normally an Arduino-based board can power the sensor - do you need the 4xAA batteries?”
The NodeMCU esp8266 card has a 3.3V output.
The sensors must be supplied with 5V.
“Can you connect both sensors”
As I only have an analogue input on a nodeMCU, I can only connect one sensor at a time, so I actually tested one and then the other.
“Triple check the solders to see if any of them have a short, or perhaps a cold solder. The three used for the barrel connector don’t look good at all.”
Quite, it could be that, I did have to re-solder (you don’t just need a soldering iron and tin to get it right, it’s years of training). And yes, I had trouble with the barrel connector.
But I find my 12v voltage a little further in the circuit, so it’s ok. It’s an ugly soldering, but it’s ok. Which is why glue was used.
It doesn’t prevent me from checking again, with a magnifying glass.
Keep us posted. Bit of a head scratcher. These are mass produced and any issues customers have reported have been caused by custom code, improper soldering or improper electrical connections. Both circuits are so basic that none of the components or PCBs have been found to be faulty.
Do you have a normal Arduino microcontroller you can test with?
#define analogPin A0 /* ESP8266 Analog Pin ADC0 = A0 */
int adcValue = 0; /* Variable to store Output of ADC */
void setup()
{
Serial.begin(115200); /* Initialize serial communication at 115200 */
}
void loop()
{
adcValue = analogRead(analogPin); /* Read the Analog Input value */
/* Print the output in the Serial Monitor */
Serial.print("ADC Value = ");
Serial.println(adcValue);
delay(250);
}
So I redid a few welds that I wasn’t sure about. I reattached the power connector to the perimeter cable.
To make sure that the connector added to the power supply is well connected, I used crimped connectors in shrink wrap (visible on the picture)
The + in the center of the connector and the - on the periphery of the connector.
Nevertheless, what I can say is that the sensor card seems to work, because I have values that go up (it was the case before). When I disconnect the data cable, I drop to insignificant values (noise 12 or 13 the value) on the Analog input.
This time I power the sensors in 3.3v, they don’t seem to care, via the NodeMCU.
Well, I skip the arduino test which is not more conclusive (in 5v).
I wonder if I didn’t break something. You can’t make an omelette without breaking eggs.
I’ll come back to you if things get better…if not, I now know the Roboshop store…
