I am attempting to display information on a Futaba Vacuum Fluorescent Display (VFD) (apologies for the google-drive link to the datasheet. I lost the original and couldn't find it again). I'm intending on using a MSP430 to do so (though I'm not so far ahead yet).
My intent was to test the device using a serial-connection from my PC, firstly via a COM port, now via a Platronix USB RX/TX thing. However, despite having the correct baud-rate (and trying others to be sure), I keep getting garbled text on the display.
Of course I've no doubt some of the experienced people here could tell me the correct way to archive this, what I'd like to know is "how can I figure out what's wrong?"
I've a tiny hobby budget of tools and not even enough for a second-hand oscilloscope, I've two (barely) decent multimeters, a Very Cheap Nonspecific USB logic-analyser from China, as well as a surprisingly decent stock of PIC, ATTiny, and MSP430 chips, opamps, etc (that I got as a "job lot") from a friend.
Every thread/tutorial/etc I see recommends either using a oscilloscope (that I don't have, and I will buy when I can afford to) or just "a logic analyser will help". Worse I can find very little information on the "SBUSY Handshake" serial communication this device uses.
Thus my question is:
- How, given my limited resources, how should I go about debugging the connection to control this device?
- Should I consider trying to build other circuits to debug this one?
- I considered trying to use the ADC of the MSP to make a "ghetto" USB oscilloscope
- Can my PC (with several RS232 ports, that is very powerful by enthusiast standards) be of any help to me?
- Should I give up without better tools?
- What should I look for with my logic analyser?
- Is watching the RX and TX line enough? Should I look on the VFD module itself?
- Is there anything "obvious" in the "SBUSY handshake" the datasheet describes that I have missed?
- Am I trying to do particle physics using a stone-club and a burning twig?
Apologies if this is somehow a duplicate ~ All the similar questions seem to be more along the lines of "show me how to do this thing." Which doesn't sit well with myself, I would much rather a "show me how best to approach debugging".
I've years in hardware-level C/C++ development, but mostly though PC architecture (rarely does one need to set their own registers and such). And for the last year I've been broadening my horizons with EE – I'm not afraid of hard work, or hard learning (you don't spend years programming C++ if you are). I want to understand what I'm doing properly, and I do appreciate not having the best tools isn't going to do me any favours, however giving up until some point down the road doesn't do it for me. Nor does plug & play shield-things.
I apologise for the generality of this question, unfortunately I don't know where else to go, or how better to phrase it.