RC car with ATtiny85

Hi!

So I want to make an rc car using an ATtiny85, a JY MCU Bluetooth module, and two dc motors.

(I'm using Bluetooth just because it's easy)

The ATtiny85 only has two digital output pins. I know I could control the motors using transistors, but that would limit them to only 1 direction.

I'd like to keep this car as small as possible, but it would also be nice to control motor direction and speed. Can I accomplish this with only ICs, or do I need to upgrade to a bigger controller?

CantSayIHave:
I'd like to keep this car as small as possible, but it would also be nice to control motor direction and speed. Can I accomplish this with only ICs, or do I need to upgrade to a bigger controller?

Seems to me there is some mutual exclusion in your goals so I'm going to go with "no" and "maybe". I suggest ordering the goals by importance...

Physically Small
Left / Right Direction
Fore / Aft Direction
Speed Control

...then be prepared to compromise (drop / change the bottom one or two goals).

What are you talking about? There are 5 pins on the tiny85 - 3 of them can also be used as analog inputs, and 2 or 3 of them (depending on the core, it seems - 3 is possible, but some seem to only give you two) can do PWM.

I really wish the Arduino people didn't harp on this imagined distinction between analog and digital pins, i think i see someone posting here who's confused on this almost daily.

All the IO pins on any Arduino-like board can be used as digital IO (except for A7/8 on the SMD version of the 328p - Atmel bungled that)

Some pins, which Arduino decided should be called "Analog Pins", can be used to measure analog voltages, in addition to all the usual functionality. By calling them that, they imply (wrongly) that the pins are inappropriate for digitalWrite()/Read, and (also incorrect) that you could use analogWrite() with them (wouldn't you think "if I use digitalRead() and digitalWrite() on a digital pin, i need to use analogRead() and analogWrite() on analog pins"? But ofc, that's all wrong.

/rant

DrAzzy:
What are you talking about? There are 5 pins on the tiny85...

I assume three would be preoccupied servicing the JY MCU Bluetooth module.

Thanks for all the feedback!

So I decided on using one of the outputs for forward/backward (for both motors) and the other for a servo to control a wheel assembly on the front. As for inputs, I only need one, for the bluetooth TX.

What I’m stuck on now is the Arduino ISP.

I have every component necessary except for the 10uF trimming cap. I have five 100uF caps, but no 10. Will a 100uF work for trimming?

Trimming? Or disabling auto-reset?

Well I guess I read somewhere it’s a trim cap, maybe I was wrong. Either way, all the ISP tutorials say to use a 10uF

100µF should work fine. Mind the polarity.

You don't have to use a servo if you don't want to. You can use 2 pins for each motor and one for receiving from the Bluetooth module. So 5 in total.

PS. Just noticed that you want to control the speed as well, then you will need 3 for each motor I'm afraid so you'll have to use a servo.

PS. Keep in mind you'll probably have to use a half bridge of some sort to run the motor(s).

Hi,
Sorry to be reactivating the topic after all this time. I'm looking for the same things for my project.
A small car as small as possible, controlled by a cell phone maybe using a hc-06 ..
Were you able to solve the problems you were encountering in development?