That is an interesting idea, but not something I have tried, I have treated each display by themselves.

I don’t think the standard library in Arduino would be able to do that, but a few hacks might get close. I would probably look in the direction of letting all displays “see” the complete picture, and then give each a “viewing window” to display. This way, you can also decide to have a little spacing between the viewing windows, since there will be a bit of distance in the real world. Scrolling or circles will look weird if they jump from one display to the next.

If it’s just a uniform scrolling, you might be able to just start each display with a certain time delay, and the same “animation” and you will end up with something that looks like a continued motion, but it’s a hack and not efficient coding

I hope this is useful for you project.

/Thomas

I was wondering if you had tried to connect the LCD displays together within the code so that, for example, you could have a message that scrolled across all 4 displays?

I say this because I am currently working on a project using an array of the Nokia 5110 LCD screens and it would be extremely useful if you could give an insight into how you might go about having an array of LCD screens physically but coding them as one large screen.

Cheers,

Ben

Best,
David

Simple serial communication with an RX and a TX line comes in a few different variations, and the primary difference is the logic levels. For TTL, it’s logic levels between 0 and 5V (or 3.3V depending on the hardware), where RS323 is between -12V and +12V. There are little chips (e.g. MAX232) that translates between the two, if you need it.

All the RFID readers I have looked at uses TTL level serial communication, but if you find one that is nicely packed up in a case with a D-SUB 9 connector on it, there is a good chance it’s RS232. Back when computers had a serial port, it was also RS232.

In most cases, the serial ports on micro controllers are TTL level UARTs, and the logic levels follows the standard for the micro controller.

As I read the data sheet for the Netduino Plus 2, it should be possible to connect 4 RFID readers, one on each serial port.

If you need a lot of RFID readers looking to see if you can get a model that communicated via I2C or similar might be a better option, since you can then put them on a bus, have way less wires and probably also simplify your code, but unfortunately I don’t have a model to point you at.

I hope it helps you and feel free to ask again if I miss something or you have other questions.

/Thomas

Thank very much you for your support.
David

The easiest would probably be to simply copy and paste 5 times and just rename so that every servo has their own code/circuitry. There might be a pretty way of writing that in VHDL, but i’s not something I can remember at the moment, sorry.

If the servos are moving together and not individually, you could probably optimize it a bit, but it all depends on the use case.

Hope it helps,

/Thomas

I guess you are talking about the Casio fx350es or something similar, right? Even though it could be fun, I can think of a lot of other projects that I would rather spend time on. Calculators are often custom silicon with all features put together in one “blob” and difficult to interface with. But I do have some graphics display modules that I will probably use in some projects in the future.

If you really need to save pins, one option is to unload the LCD control to a separate chip, eg. another avr… there is even a sketch in the Arduino environment that makes a serially controlled LCD. That sketch could probably be modified a little to be able to control multiple displays and only require a single I/O pin from the main controller to run some UART commands (could probably be soft serial if the hardware serial is occupied).

Using shift registers or I/O expanders is probably also possible, but I haven’t tried it myself.

I hope it helps,

/Thomas

This bootloader should also work on the ATmega8A, worst case is that you will need to recompile it, but I don’t even think that is necessary. Selecting the clock is actually not part of the boot loader, but the fuses set during programming. There are various online tools to help you find the right fuse bits to use if you want to change these, just be careful, there are also fuse bits that lock the firmware.

Thanks