65XX SBC general help and color display help needed

[backspace119]

I've been way busier than I expected for the past little bit, but I'm about ready to send this design off to have the board made, Here's an image of the schematic, board routing, and 3d view:

schematic.pdf

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board.pdf

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Any glaringly obvious details I missed?

[backspace119]

I did some clean up and have saved about 100 vias so far, I'm hoping by the end of today I can send it off, I've been incredibly busy recently (yet again) so this has fallen by the wayside. If anyone has any input on the design (schematic) it would be much appreciated, I think I've accounted for everything but I'm not certain.

[backspace119]

So, I think I've reviewed it pretty well at this point, I have another question on the board though, should I go for a HASL finish or ENIG gold? it's about a $20 ($4 per board) difference, and most of the boards I've worked with in the past were ENIG, although I've seen a few HASL from time to time.

[GARTHWILSON]

There's nothing at all wrong with HASL—unless there's something about marine applications perhaps, where salt is a problem. 

[backspace119]

GARTHWILSON wrote:

There's nothing at all wrong with HASL—unless there's something about marine applications perhaps, where salt is a problem.

Ok, as far as selling the spare boards, is it legal to sell leaded HASL boards? I don't think any of the guys I've talked to live in California, if that helps.

[GARTHWILSON]

If the solder is leaded, you're not supposed to sell it to Europe (because of the RoHS); but for the negligible quantities you're likely to sell, I don't think anyone is going to care.  Now if it were a consumer-volume product like cell phones, they might not look the other way.  At the company I work for, we always go for hot-air solder leveling and leaded solder.  We buy 5,000 boards at a time.

[backspace119]

GARTHWILSON wrote:

If the solder is leaded, you're not supposed to sell it to Europe (because of the RoHS); but for the negligible quantities you're likely to sell, I don't think anyone is going to care. Now if it were a consumer-volume product like cell phones, they might not look the other way. At the company I work for, we always go for hot-air solder leveling and leaded solder. We buy 5,000 boards at a time.

Alright that sounds good, I prefer leaded solder anyway, I've had some bad joints with non leaded solder before. So that makes all 5 boards only about $45, which is honestly a steal. I'll definitely be having more boards made at JLPCB if these first ones turn out well.

[drogon]

GARTHWILSON wrote:

If the solder is leaded, you're not supposed to sell it to Europe (because of the RoHS); but for the negligible quantities you're likely to sell, I don't think anyone is going to care.

The lead issue is to do with consumer goods sent to land-fill (at end of life, hopefully). It's perfectly legal to buy and use leaded solder for hobby/non-commercial projects and IMO preferable if the stuff I've read about the lead-free flux is true... See for example: https://uk.rs-online.com/web/p/solders/0555235/ you just can't sell items made with leaded solder. (Although there are exceptions).

I have the option of buying PCBs from the Chinese PCB place I use, which come with a lead-free HASL finish too, although it adds about $8 to a batch of 10 PCBs.

-Gordon

[GARTHWILSON]

drogon wrote:

It's perfectly legal to buy and use leaded solder for hobby/non-commercial projects

That's nice to know.  Is that true for all of Europe, or just UK?  I was not involved in the decision at our company.

[Chromatix]

I don't think there's any difficulty in obtaining ordinary lead-tin solder in Finland, from Germany.

I think the rule of thumb is: if you're building it by hand and not mass-producing it, the RoHS regulations need not be applied in full.

[backspace119]

Today's the day! Everything has finally arrived (the boards came via DHL even though I selected UPS, so I'm thanking my lucky stars they made it here, and in one piece). I'll try and take pictures to document the process as I go along, I've already tested the boards and connectivity seems great. The box of parts from mouser was way bigger than expected, probably because packaging for a lot of components is pretty large compared to component sizes.

So now I just need to get everything laid out and a game plan down for soldering and testing. First I'm going to get the power stuff put on, power it up, and confirm power is being delivered correctly.

[backspace119]

Power phase is done and working, the Red 12v good light is incredibly bright, the green 5v good is much more acceptable. I'll post pictures after I'm done

[backspace119]

I'm taking my first break from building now and I'm sad to say I've found a few bugs with the board. Luckily, none are life threatening to the computer, they're only fitment issues of certain parts, and only one of which I was unable to rig to get it to work.

First, the composite video out jack had a vertical square peg on the center back instead of horizontal, I drew the footprint for it since kicad didn't have it, and I was pretty sure I was thorough, but I must've missed it, because I made the hole a horizontal slot.
Second, the cartridge connector holes have too small diameter for the pins to fit very far into them, I was still able to get it soldered, but it's standing off the board a bit, the pins are conical with slots in the center, and I must've not used the top diameter for the holes (made that footprint too).
Last, and this is the worst one, the D-Sub 9 connector for RS-232 is unable to accept the jack I ordered, and probably any jack for that matter. The pins are right, but it doesn't have the board holes for the mounting pegs. I didn't make this footprint, but relied on one provided by kicad. My best hope is to cut the pegs off of the connector, and be careful when attaching and detaching cables, or, I may make a standoff board that connects to it, and has the correct footprint on it.

Overall, everything is going smoothly, I've got the CPU, both VIAs, UART, MAX232, 65SPI, header for 4M memory module, some capacitors, the power phase, digital pot, trimmer, reset circuit, UART clock, 32k SRAM, RTC and a few gates installed so far. One other unfortunate truth I learned was I forgot to order the LTC1799, the clock generator for the board. This is ok though, since I'll need to spend a few days programming the EEPROM with an arduino anyway, and it will get here by then (actually I ordered the LTC6900, it's worse than the 1799, but the 1799 was on backorder).

I'm very excited to get this up and running, can't wait to see the first hello world.

[BigEd]

Thanks for the update. It's useful to hear about these little bumps in the road: we can all learn from each other.

[backspace119]

So, as it turns out, I ordered a 74AC11008 instead of a 74AC11 for one of my chips. I've found that the 11 doesn't come in any form except LS (at least in THT package). I ordered a big box of LS and HC chips off amazon because I already had a mouser order in, and they wouldn't let me cancel or update it with more items. Also, I forgot to order the eeprom (although I'm certain I did) so I ordered a 150ns eeprom off amazon too. All that will be here tomorrow, and I'll start programming the EEPROM then, until then, I'm going to brush up on some 6502 assembly and find a starting point. I think I'm going to hardcode a hello world in eeprom as my first setup, just to see the thing run.

A side note on the 74LS11, the delay on it is 15ns, but this may be for TTL output level, I really don't have any other choice, so it doesn't matter, but I'm hoping it's still fast enough not to get in the way. All it gets used for is interrupts and the active high enable for the 3 to 8 I/O selection chip, so at the very least it won't affect anything other than that.