Problem with ECU

Other Hardware Motors, Mechanics, Power and CNC
1

Hi all,

I'm working in a project that is about a construction of a device based on an embedded system that will replace the sensors and simulates
electrical failures in machines by changing the signals that are sent to ECU.

The hardware that I am using to communicate with the ECU is the Arduino, that works with a voltage range between 0-5V, and an amplifier based on transistors for reach higher voltages. With only the Arduino connected, the ECU recognizes the signals and makes the appropriate changes in the front panel, but when connected with the Arduino and the amplifier circuit, the ECU don’t recognizes and nothing happens. So I would be grateful if someone could help me with some advice about the electrical system involving the sensors and the ECU.

Thank you for your time.

2

It sounds as though the problem lies in the amplifier... but you haven't provided the schematic of the amplifier.

3

the transistor is the TIP120.

tks.

4

Rafael5767:
the transistor is the TIP120.

What transistor? There isn't one in your schematic.

5

Sorry, wrong figure.

6

Whether that circuit will behave as you intend depends on the input resistance of the ECU. If it is high enough, then it will work; although TIP120 is a poor choice of transistor (you should use a small signal transistor such as BC337 or even 2N3904). Also, the 10V supply will need to be regulated, otherwise the output voltage will depend on the supply voltage.

The circuit you gave in reply #2 will work even if the input resistance of the ECU is quite low, although if V2 represents a PWM pin on a 5V Arduino, then R2 and R4 should have equal values. The output voltage will depend on the exact voltage of the 5V supply, but not on the 10V supply (as long as it is high enough).

PS - I am assuming that you have increased the PWM frequency, because the low-pass filters you are using (22K and 0.47uF in reply #2, or 10K and 0.47uF in reply #4) will not provide very good smoothing at the default PWM frequency of about 490Hz.

7

thanks for the replies,

I will try with both bc337 and the equal resistors.
And about the PWM frequency, I hadn't increase, could you give some advice about that?

8

Rafael5767:
And about the PWM frequency, I hadn't increase, could you give some advice about that?

See Arduino Playground - HomePage. Choose a PWM pin other than 5 or 6, otherwise the millis() and micros() timing will be affected [on a Uno].

9

Sorry, i didn`t understand some things.

You said to increase the frequency, but the link show how to decrease.
And.. you said that the frequency is about 490Hz, but in the link, the frequency is 62500Hz.

I`m a little confused.

tks for your time.

10

Rafael5767:
Sorry, i didn`t understand some things.

You said to increase the frequency, but the link show how to decrease.
And.. you said that the frequency is about 490Hz, but in the link, the frequency is 62500Hz.

I`m a little confused.

tks for your time.

The frequency you normally get from analogWrite() is 490Hz. The maximum frequency you can get (referred to as the "base frequency" on that page, which is not the same as the default PWM frequency) is 62500Hz or 31250Hz, depending on the pin. The link shows how you can select the frequency, which (depending on your choice) may be above or below the usual frequency of 490Hz.

11

ahh ok, now i think i understood,

the problem is that i`m working with labview to communicate with the arduino, but i found a link that maybe will help me to change the frequency through the labview.

I will try all your advices, in case of fail i will post here the doubts.

Thank you for your help and time.