Today I started to look to put the board I assembled yesterday into my Arduino Mega based remote control (viewtopic.php?f=21&t=7422&start=124). Right now I am trying to decide on IO pin mapping. Will probably start it’s own thread, or could continue on with the other thread as well…
What I am currently looking at doing is to experiment with leaving the XBEE on USART0 (which is also used by the FTDI breakout board). It will be interesting to see how reliable downloading new programs over XBEE works… Things like,need to reset XBEE to not be in packet mode, then reset processor… May be simpler to leave it off until the compile completes and then turn it on… Will experiment. This has the downside that you can be harder to debug as you can not output data to serial port… Will work on some solutions for this, plus some can be output using other things like the LCD.
Will use the 2nd USART to talk to the OLED
Analog pins A0-A5 will use for the Original 6 analogs (2 per each joystick and 2 sliders)
My Extended Analogs X0-X2 will use for new ones (rotation on joysticks, plus middle slider)
X3-X5 are Free
X7 - Voltage monitor.
Digital Pin: 0-7 will be used for keypad.
8,9,10,11 - Are the IO pins used by USART0 and 1
12-15 - Command buttons - If we get tight can reduce this down to one pin (add a row or Column to keypad), like I did with BAP version.
16-17 - Buttons on top of joysticks
18-20 - Are free - (May experiment with using a button to do a reset for download), but could this in keypad pages…
21 - Sound
(22-23 and A6-A7) - Are used in the MUX…
If we desire to try a parallel LCD We can easily reclaim some IO pins. The switches and buttons can be added to the keypad logic. Also can use X5-X5 and potentially X6 (Solder in pin for it) can be used for buttons as well, but would probably need external PU added. May be able to rig it using the underlying PU of A6/A7 when testing for these button… May experiment.
I’ve managed to control my parellel 4x20 vfd using a 74595 shift register. This means that we can control a full featured parallel display with just three pins as long as it has a 4bit mode.
I guess the question with adding a Shift register such as this, is do you end up needing another board to hold this and if so, do you still have a cost savings versus using one of the other displays with Serial or I2C connections…
Since the 74595 shift register is an 8 bit shift and you mentioned 4 bit mode, you probably put some of the other control lines on this as well? I know that a long time ago, when I built the Seattle Robotics Society workshop robot, I assembled a daughter board that controlled a Parallel LCD as well as a few other devices had 2 74595 for output and 2 74589 registers for input and they were connected to the SPI lines. I remember these chips were chained to each other so you can build whatever size output you desire.
Right now, I have the board mounted to the DIY case and am updating the code and still connecting all of the wires. There were some other issues with my earlier code that I am changing as well, like I was using DigitalWriteFast library which does not have support for the 644P, so changing back to normal digitalRead and DigitalWrite.
The way I hooked it up I used four data pins, and then the RS, RW and EN pins were also connected. This allowed Reads and Writes to the display in 4-bit mode. I did not use the eighth bit to control the display.
Yep, Serial LCDs can be nice when you are low on IO Pins, But parallel is nice when you have several free pins, as that data is that you control the timing of the data, so it less susceptible to being corrupted than the serial ones are, unless of course if you have a hardware serial port available…
Still testing the new board in the remote control. Having a few issues with timing of the secondary analog inputs. Will work it out soon, but been busy with other stuff…
Probably should continue this under Remote control, but I have been slowly working on making my DIY remote control to work with this new board.
So far I now have all of the inputs working . This includes using the inputs from the Multiplexer… Next will to be get it to work with the XBee on USart0.
Will work on making it such that maybe I can have it be programmed from the PC over the XBee. So would need to be in serial replacement mode at power up with it’s DL pointing to the the XBEE that is connected up to the PC. After it gets past the bootloader it will then switch into packet mode and start talking to whichever robot you have selected. Also since in this mode, I no longer have a standard debug terminal, so may write a quick and dirty VB app (I think I started one earlier), that my program can send debug information to and potentially get debug commands from.
With my current DIY Remote control code for this board, I have it read all 6 standard Analog inputs per pass and only up to one set of 2 of the extended ones. I then setup the extended ones for the next 2 and return. This gives a little time for the Analog signals to stabilize from the new set of pins before I try to sample them…
Having some issues with getting the XBEE to work in the DIY on USART0 with the OLED on USART1. For some reason, when I try it, the USART0 TX stream is corrupted, where the TX1 stream appears to also come out on TX0. If I don’t have my jumpers in place to enable the XBEE this does not happen. Have traced some of the IO lines so far everything appears to be OK…
Next will try unplugging the OLED display… If I make Rev 003 of the board, I am now wondering if I should instead of using the resistor divider approach for voltage conversions for the XBEE, instead go to a chip like the Parrallax adapter does 74LCV244A. Could use a large 20 pin version, that should hopefully fit under the XBEE, bit taller than I would want… I sort-of remembered having issues before with the Arduino Mega shield and the XBee/OLED until I used this adapter…
A R2R ladder does seem to be the easiest way and will perhaps use less space if SMD resistors are used. One could also look at Delta Sigma but that is probably equivalent to making a mountain out of a mole hill; not to mention the extra cost. I could not find any data sheet with 74LCV244A? Perhaps I am looking in the wrong place.
Yes, could design with SMT… Most all of the other components are SMT. My only issues are my old eyes and hands are not very good at hand soldering those really small pins… Should probably someday try making a solder mask and either try toaster oven or frying pan approach…
. This includes using the inputs from the Multiplexer… Next will to be get it to work with the XBee on USart0.