cheaper large instrument displays - mast mount

I agree that SM is the way to go for professionals and production, but don't think it is appropriate for this project at this stage where the intention is for anyone to get involved and be able to build up a system and get it working, for example would Tom Brewis have been able to cope with SM component fabrication, assuming someone had done a PCB and paid for its production?

All the through-hole components I have chosen are also available in SM versions if anyone wants to go that route, but until it is decided that the project is worth investing money in and getting PCBs made and populated, I think it is a good idea to stick with components that can be assembled on Veroboard or breadboard by people who may never have assembled an electronic circuit before. That's why YAPP projects have always used through hole.

This and all the other YAPP projects are open source. If anyone wants to layout one of them from the schematic onto a SM PCB, feel free to do so.
 
AngusMcDoon said:
I agree that SM is the way to go for professionals and production, but don't think it is appropriate for this project at this stage where the intention is for anyone to get involved and be able to build up a system and get it working, for example would Tom Brewis have been able to cope with SM component fabrication, assuming someone had done a PCB and paid for its production?

All the through-hole components I have chosen are also available in SM versions if anyone wants to go that route, but until it is decided that the project is worth investing money in and getting PCBs made and populated, I think it is a good idea to stick with components that can be assembled on Veroboard or breadboard by people who may never have assembled an electronic circuit before. That's why YAPP projects have always used through hole.

This and all the other YAPP projects are open source. If anyone wants to layout one of them from the schematic onto a SM PCB, feel free to do so.
Click to expand...

+1
I admire the neatness of SMD, but through hole is much simpler to assemble at a non-professional level (one might even use low profile sockets for vulnerable ICs). It allows you to build in stages as well, rather than "firing" the whole board fully populated. If people are confident enough to do SMD, then go ahead. I don't mind soldering discrete wires in holes in a board :)
 
Last edited:
Having fun and games with the max233 chip (my fault, I decided to rewire it to make it easier to explain and have written something down wrong)

I have the following

Rs232 pin 3 > max233 pin 4 r1 in
Rs232 pin 5 > breadboard ground
Max233 pin 6 & 9 Gnd> breadboard ground
Max233 pin 7 vcc > breadboard 5v
Max233 pin 3 r1 out > discovery board pa3

Any ideas? I have a wire left over and feel I missed a connection
 
Last edited:
ShaunG said:
Having fun and games with the max233 chip (my fault, I decided to rewire it to make it easier to explain and have written something down wrong)

I have the following

Rs232 pin 3 > max233 pin 4 r1 in
Rs232 pin 5 > breadboard ground
Max233 pin 6 Gnd> breadboard ground
Max233 pin 7 bcc > breadboard 5v
Max233 pin 3 r1 out > discovery board pa3

Any ideas? I have a wire left over and feel I missed a connection
Click to expand...

Datasheet for the MAX233 says connect pin 9 to ground as well as pin 6.

If it doesn't work, try swapping RS232 pin 3 for pin 2. The RS232 pin the data will be coming in from could be either of these pins depending on what is on the other end.
 
Thanks Angus..I just noticed that pin9 was the secondary ground and connected it..which explains the missing wire.

Still no joy though, I can see the voltage changing on the serial port and to a much smaller degree on the output from the max233.

Cn I just check that it was pa3 on the disco board

I used this one as it needed to caps
 
ShaunG said:
Thanks Angus..I just noticed that pin9 was the secondary ground and connected it..which explains the missing wire.

Still no joy though, I can see the voltage changing on the serial port and to a much smaller degree on the output from the max233.

Cn I just check that it was pa3 on the disco board

I used this one as it needed to caps
Click to expand...

NMEA input on PA3.

You could try it the other way round. Debug output is on PA9 at 115200 baud. When you press the reset button it should output a line of text if you have that in your source. Look in main() for serial1_send_string() and check that #define DEBUG_PINTS is in mast_display.h.
 
Sorry if this was answered earlier in the thread (I've been dipping in and out)...I recognise you're trying to keep costs low and indeed I was using a max3232 for nmea to a pi-based project I posted about recently, but for a more "robust" application why are you not looking at an optoisolated rs422 input? (this is a question, not a statement as I'm a rank amateur at this electronics malarkey)
 
laika said:
Sorry if this was answered earlier in the thread (I've been dipping in and out)...I recognise you're trying to keep costs low and indeed I was using a max3232 for nmea to a pi-based project I posted about recently, but for a more "robust" application why are you not looking at an optoisolated rs422 input? (this is a question, not a statement as I'm a rank amateur at this electronics malarkey)
Click to expand...

That is the plan, just not got round to it yet.
 
Thanks Shaun for posting the pinouts. I will check mine in a moment.
Angus your are absolutely right about my lack of skills, just hanging on by finger nails, but v enthusiastic.

All the best

Tom
 
I have just connected up as per the last posts on the MAX233CPP, and I had not provided a power supply or the second ground, but now all is working. Very happy as I had bought a new MAX233 today from RS, so if anyone needs one I have a spare.
I post some pictures below the quality is even worse than my usual output as I am staying in a hotel at Gatwick at the moment and the lighting is not good.
Don't know what the chambermaid make of all the wires etc.. all over my desk!!!
 
Hi Tom, when you get a chance could you list out your rs232/max232/disco board connections? I seem to have buggered mine up

The led control is driven from the pwm output via a opamp? This allows control of the backlight level
 
You must log in or register to reply here.

Share this page

Top