While waiting for the Panda’s, the PCB from the manufacturer and the components from Sparkfun, I’m creating another board for a (long term) personnal project.
Here are its actual specs :
- precision drive 1 or 2 bipolar steppers
- have many digital IO’s
- have many analog inputs
- have as much relays as possible, including SSR relays
- link to a computer via the network for data acquisition
- leave as much free pins as possible in the shield header, so that other shields can still be used
For the steppers, after some trials, I finally decided to use the EasyDriver board directly on mine. This way, you can put 1 or 2 boards, or even none if you don’t need it…
Here, I’m using 4/8 pins from the UExt connector.
For the digital IOs, it’s almost the same thing as the board sold here at GHI. I2C permits the use of only 2 pins for 40 IOs.
For the analog inputs, I’ve chosen a ADS7830 that offers 8 channels at 8 bits precision. I don’t know if 8 bit is really enough though :think:
This chip is also driven by I2C, so no pins used.
For the relays, I will have to choose smaller ones, I think. I didn’t have time yet for this. The SSR are too big, I think. I know that DIP6 relays exist, so I will try to find them.
These will be connected to the extra-IOs I get with the PCA9505, so again : no shield pin used. They are not yet connected on the prototype below.
For the Ethernet connection, a Moxa 4100T can be put in the middle of the board. This one eats the COM1 pins, though
So, if I summarize with a complete board (2 steppers and the Moxa), that’s :
- 2 stepper = 8 UExt pins
- Moxa = 2 shield pins (COM1)
All other shield pins are available. I think this is good. Even though no COM port is available because the Moxa is used for communications between PC and board.
What do you think of this ?