gjohal
Canada
Asked
Resolved by ptp!
I have an Omnibot 5402 that I would like to control movement and move the arms and head to start. I was thinking of going with the smaller EZ-B IoTiny due to cost difference and lower port requirements. The EZ-B IoTiny has 8 digital ports and a dedicated camera port. Since all I want to do is run the motors for movement by using an H-Bridge and 3 HDD Servo's for the arms and head movement, the IoTiny should work. If later on I add a Camera and Ultrasonic sensor and a Display/LED, I should still be able to do this with amount of ports on the IoTiny. Any thoughts on going this route?
Related Hardware EZ-B IoTiny
The solution is Elementary mathematics.
EZ-Robot H-Bridge: https://synthiam.com/Community/Tutorials/44 You have 2 ports left (D6, D7) for 2 servos. Option A) Ultrasonic Sensor: "Over the counter" 2 digital pinsOption B) EZ-Robot https://www.ez-robot.com/Shop/AccessoriesDetails.aspx?prevCat=9&productNumber=6 1 digital pin LED one color : 1 Digital Pin
So: 6 - EZ-Robot H-Bridge 3 - 3 x Servos 1 - Led 1 - EZ-Robot Ultrasonic Sensor Total = 11 Digital Pins
Unless 11 is equal to 8. I don't think you can fit all with an IoTiny.PTP: Thanks for explaining the need for 6 Digital pins just for the H-Bridge. I definitely need the EZ-B V4 then, even if I decide to keep it simple for now, I would use up all the pins with just an H-Bridge and 2 servo's and no upgrade room with the IoTiny.
Just wanted to add that you can use an H-bridge with 4 or 5 wires instead. 4-wires removes the PWM speed adjustment completely but it's still fully functional. With 5-wires you can have one wire that changes the speed of both sides of the H-Bridge at the same time. 6-wires is only used for independently controlling the speed of the motors, which is not always required.
You can also use the IoTiny I2C port with a port expander to get more I/O. I don't have an example of that but I'm sure you could find code out there.
You also have access to 2 x ADC ports on the I/O tiny that can be used for distance sensing. I know that Maxbotix has Ultrasonic sensors that can output an analog value.
Jeremy, thanks for the additional options mentioned. I may still go with the V4 as it's the best to build on and may be simpler if I add on sensor's later.
If you remove the pcb from a servo, it becomes a speed controlled hbridge via one port. And, the continuous rotation servo Movement Panel makes it easy.
I like using servo pcb’s as tiny hbridges. I’ve convinced Jeremie to do it often in his robots.
Ps, I recommend a camera right away rather than waiting. A robot without a camera isn’t a robot :)
Thanks for the tip DJ, lots to digest before making a choice.... My Omnibot is an original one I had as a kid, no camera, but I definitely considered it a robot in 1984!