So the first batch of PCBs for the DRO display have arrived. Looking good.
First problem, I made the holes too small for the header pins on the Nano and OLED display.
Drilling will remove the thru-hole plate so since this is a prototype, I will use strip sockets with smaller pins to mount these.
I plan to use a SMD ATMega328p TQFP chip on the final board. the final board will have a FTDI and ICP header.
I also purchased a TQFP 32pin socket to allow me to pre program the chips.
Still waiting on some voltage regulators and shottky diodes to complete but have enough bits to make a start.
Hooked up three sensor boards, the Nano and the OLED. modified my single axis code to support three.
Seems to be working well. Basic code fits in about 13k program space. No noticable lag in display update.
The encoder read happens every 50mS and the Arduino seems to cope with this.
Remember that most of the work is done by the LS7366 Encoder/counters. The LS7366’s sole purpose being to count the pulses from the AS5311 encoders and store the count. All the Arduino needs to do is retrieve the count over the SPI bus and display to the OLED in either metric or imperial. No interrupts needed….
Next step is to add the zero and metric/Imp switches for each axis (6 switches). I’m planning on doing this with one analog input and six 1k ohm resistors in a ladder configuration. So here’s the schematic with the planned switches. The switch portion being untested so far.
The display font is a scaled 5×7 pixel standard font. As shown in the photos, it is scaled twice size so looks a bit blocky. I’ll look at adding some better looking fonts so the layout looks better. One I confirm the switch design is working, I will re-design to use a smaller PCB with a SMD ATMega328p. I’ll also add a jumper to select the default measurement unit at power on. Currently this is set to imperial but can be changed on any axis by the push buttons.
These OLED displays are really impressive. I originally planned to use standard MAX7221 driven seven segment displays as seen in the first prototype but after using these OLEDs, I can’t see the point. I’ll include a 3 channel SPI header on the final board for anyone that wants to stick with seven segments, but OLEDs are now my favourite.
For those who are keen on the seven segments, here’s the schematic.
One for each axis. Use either MAX7219 or MAX7221. Datasheet is online.
Hello friend, I want to assemble a dro for my mill, would it be possible to use it with linear scales?
If you have linear scales that output quadrature signals, then yes. You would need to know the quadrature count per mm. You would also need to know the pin out of the scales to be able to identify the A,B quad signals and power connections.
I don’t know if they will be in quadrature, I know they are the famous shahe, I think it uses a 24-bit protocol, or bin6 protocol, the rest no idea. It has power at 1.5v, clock and signal try to add a 3rd axis from a sketch of a Russian forum, but I can’t get it and I was looking at more options, The forum is this. https://www.chipmaker.ru/files/file/11832/.
I believe that is a serial protocol. Very different to quad signals. My DROs are not compatible with the 24bit protocol.