acs712 entegre

ofSsBe · 27. February 2008, 03:41 PM

Merhaba arkadaslar

ACS712 entegre hakkinda dokuman lazim akim trafosu olmadan 30 ampere kadar akim olcuyormus sanirim. Kaynak bulamadim dogru duzgun.

**PIONEERNADIR** · 27. February 2008, 03:52 PM

Alıntı:

ofSsBe´isimli üyeden Alıntı

Merhaba arkadaslar

ACS712 entegre hakkinda dokuman lazim akim trafosu olmadan 30 ampere kadar akim olcuyormus sanirim. Kaynak bulamadim dogru duzgun.

Akadşım ben döküman buldum umarım işini görür..

[Sadece Üyelere Linkler Açıktır.Üye Olun !!! Tıklayarak Üye Olun !!!]

**PIONEERNADIR** · 27. February 2008, 04:30 PM

After the near mishap with the last GPS bush walk I have pondered how I was going to monitor the battery power usage. This blog is my first go at it.

I found this neat [Sadece Üyelere Linkler Açıktır.Üye Olun !!! Tıklayarak Üye Olun !!!]. The ACS712 runs off of 5V and can monitor up to +- 5A with an internal resistance of only 1.2m Ohms. Unfortunately it comes in a SOIC-8 package which is something I haven't used before. Maybe it's time to build a [Sadece Üyelere Linkler Açıktır.Üye Olun !!! Tıklayarak Üye Olun !!!]? I don't have a milling machine so the next quickest thing was to solder up my own. It is build by hand soldering some wire rap wire to pins 5-8 and cat5 wire to pins 1-2 and 3-4. I used some male header pins soldered onto a small piece of vero board. All very messy (no pics) but it works.

Really I should be using the [Sadece Üyelere Linkler Açıktır.Üye Olun !!! Tıklayarak Üye Olun !!!] as that monitors from 0 to 10 Amps. unfortunately I don't have one of those at the moment.

I am using a PICAXE-8M chip to handle the AD conversion. There is also a resistance divider so I can monitor the 12V battery voltage. At the moment I am thinking it will just average out the measurements and output a current/voltage string on the serial port roughly once a second or maybe just output the string upon request.

Here is an EAGLE schematic of it all:

Here is the test board layout for it all:

The board layout is not quite correct as I need to create a better ACS712 SOIC device layout. Anyway you get the idea.

Testing the circuit on my bread board I found out that I can measure the voltage in steps of around 196 mV and current to 100 mA steps.

Here is the test PICAXE-8m program I used to monitor the battery voltage and current usage:

Kod:

' this will monitor and report the 12V Battery and Current being used
'
' Paul Hamilton - Sept. 2007
'

' Local Variables
SYMBOL LOOPDELAY=500

MAIN:
' Blink a debug LED - one reading per blink/loop
high 1 ' set the LED on port 1 ON
pause LOOPDELAY
low 1 ' set LED off
pause LOOPDELAY
' lets read what the voltage is on the resistance ladder junction
READADC 2b1
' lets read what the current is being reported by the ACS712
READADC 4b2
b3=b2-126
' because I am using a ACS712 Need to watch out for readings below 0 (ie 255)
' I really should be using a ACS713 then I wouldn't have this problem. 
if b3<253 then SKIP
b3=0
SKIP:
sertxd ("V: " #b1" A: " #b31310)
goto MAIN

Now I have to build the circuit board. A circuit and board to monitor the propulsion motors will need to be designed and built. Luckily I have an Allegro ACS754 which can handle up to 50 Amps!

Also check out [Sadece Üyelere Linkler Açıktır.Üye Olun !!! Tıklayarak Üye Olun !!!] in this series on the design and building of the PC Battery Monitor.

I have attached a set of Eagle schematics for those that are interested:

[Sadece Üyelere Linkler Açıktır.Üye Olun !!! Tıklayarak Üye Olun !!!]
[Sadece Üyelere Linkler Açıktır.Üye Olun !!! Tıklayarak Üye Olun !!!]

**PIONEERNADIR** · 16. April 2008, 01:58 AM

In [Sadece Üyelere Linkler Açıktır.Üye Olun !!! Tıklayarak Üye Olun !!!] of this project I developed a test circuit that proved that it would all work. In Part II I actually redesign the bread boarded prototype into the final product.

I had thought to integrate the Motor battery V/A and the PC battery V/A onto the General Purpose PICAXE-40X board. However I was struggling to come to terms with bringing the power cables into the PC housing. I thought it would be best to locate a sub-board close to the motor battery and route the serial output back to the GP PICAXE-40X board. Also this small board can be used right now in my GPS exploring walks etc.

Whilst the first circuit did work it relied on the PC to monitor the Battery Voltage and Current being used. It would be nice if I could display the actual values - live and have a buzzer that would alert me when the battery falls below a set voltage. This required me to upgrade to a PICAXE-18X chip. I also took the opportunity to redo the ACS712 SOIC-8 layout within my Eagle library.

After a few iterations at designing building prototyping on the breadboard and then writing up the schematic diagram and board lay out etc I ended up with this layout:

I enjoy doing board layouts. Nothing quite like playing around in a good maze of copper! At each stage I have uploaded a copy of the files to my Subversion repository. Incidentally there are about 328MB of files in this section of the repository. The project has now been running for over 2 years.

And here is the board layout (as it stands today):

You can find a copy of the Eagle files at the bottom of this page.

The PICAXE program didn't have to change all that much and is still quite small:

Kod:

' this will monitor and report the 12V Battery and Current being used out to a serial port
' at 4800 bd. This is to be used with the SWASC Power Monitor - Computer circuit.
' This uses a PICAXE-18x so the current and voltage can be displayed onto a 2 x 16 line LCD
'
' Paul Hamilton - 20070916
'

' Local Variables
SYMBOL LOOPDELAY=500

' clear the LCD screen
serout 7N2400 (2541)
pause 30

MAIN:
' Blink a debug LED - one reading per blink/loop
high 1 ' set the LED on port 1 ON
pause LOOPDELAY
low 1 ' set LED off
pause LOOPDELAY
' lets read what the voltage is on the resistance ladder junction
READADC 1b1
w2=b1*10/16 ' convert the reading from units to voltage * 10 ie. 119 = 11.9 Volts
' lets read what the current is being reported by the ACS712
READADC 0b2
b3=b2-121
' because I am using a ACS712 Need to watch out for readings below 0 (ie 255)
' I really should be using a ACS713 then I wouldn't have this problem. 
if b3<253 then SKIP
b3=0
SKIP:
sertxd ("V: " #b1" A: " #b31310) ' send data to PC
serout 7 N2400 (254128"V: "#w2" ") ' display the Voltage. Need to mentally divide by 10
serout 7 N2400 (254192"A: "#b3" ") ' display the current. Need to mentally divide by 10.
if b1>197 then MAIN
sound 6(110208030) ' plays a Voltage Low warning sound
goto MAIN

The PICAXE AXE-033 LCD displays the battery voltage x 10 ie. 'V: 124' where you have to mentally divide by 10 so that it should read 12.4V Same with the current. The smallest current level it can sense is 100mA. If I included a LN321 op-amp I could get it down to read 30mA per unit. But for now 100mA is ok. Also I don't have any of those op-amps but I do have quite a few of it's larger cousin the LM324. Since I don't have any of the LM321 chips and that none of my usual vendors don't carry it I skipped it all together.

Lastly here is a shot of the bread board testing setup:

I am loading down the 12V 5A/Hr battery with a 5 ohm resister (near the top right hand corner - yellow alligator clip). I am drawing 2.1 Amps and the battery is reading 11.15 Volts. I also have a cable running to my PC. All good fun!

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[Sadece Üyelere Linkler Açıktır.Üye Olun !!! Tıklayarak Üye Olun !!!]
[Sadece Üyelere Linkler Açıktır.Üye Olun !!! Tıklayarak Üye Olun !!!]
[Sadece Üyelere Linkler Açıktır.Üye Olun !!! Tıklayarak Üye Olun !!!]

ULAGA · 21. November 2012, 06:52 PM

Konunun mesajları tekrardan düzenlenmiştir.