Rank: Member
Groups: Member
Joined: 1/2/2017(UTC) Posts: 3 
|
Hi, i bought the pcb for JT and Volumite uP few months ago. Now i have builded the i2c controller on my own PCB with Attiny,MCP23008 and ULN for driving the relais.
Everything works fine, but in some cases i am able to "find" the position on potentiometer, where some relay starts to oscilate with high frequency. I tried to separate the supply voltage to the coils on JT from another PSU, which does not solve the problem. Is there any other thing to watch out ?
Thanks, Petr
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 1/2/2017(UTC) Posts: 3
|
OK, small progress. As i had not the vreg for 5V on board near attiny it looked that was the point, why the relais starts to oscillate, the uP is really sensitive to the 5V PSU stability. Now i have 7805 on pcb near Attiny. Nevertheless, when i tested the circuit with multi turn trim there is still one point where the relais started to oscilate. Vcc is 5,028V and at 2,1238V on trim wiper thats the point where last two relais oscilating like a motorboat :D
|
|
|
|
|
|
Rank: Administration
Groups: Administration, Customer
Joined: 10/24/2006(UTC)
Posts: 2,868
Location: Massachusetts, USA
Thanks: 2 times
Was thanked: 141 time(s) in 134 post(s)
|
This is usually a sign of not enough driving current, which is affecting readings of the ADC in the uC.
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 1/2/2017(UTC) Posts: 3
|
Hello, after 5 years opening this topic again. I realized that in Volumite schematics there is 3V3 reg, but i have used my own design and populated 5V reg for Volumite ! Relay driver has its own 5V reg. According to datasheet, MCP23008 expect 0,8*Vcc on SCL/SDA lines what equals to 4V. So what is the correct Vcc for Volumite uP ? Is it 3V3 (and how it works wit relay driver which expect at least 4V on lines) or 5V ? Thanks for reply.
|
|
|
|
|
|
Forum Jump
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.
