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NEW BOARD V1.2 with tons of fixes from PCBway !

A project log for Multichannel Audio DSP Field Mixer Recorder

USBmidi, bluetooth app controll 8 chan portable DSP mixer.balanced audio IO,phantom power,flexible routing,ISO recording. networked Timecode

ben bilesben biles 01/24/2019 at 06:570 Comments

Horray the new 4 layer board is here from www.pcbway.com and I made tons of fixes :) + its got gold contacts !!! oooooohhhh :)


The quality of this board looks awsome. I checked the upgrade for free box if available and got what looks like gold contact  for free, wow ! 

I have used smaller IO sockets , 1.27mm so I could free up some space for cool things like a 1" OLED screen to help with checking Bluetooth control is working properly. I managed to sneak on 2 I2C RF module sockets to. what are they for ?

Digital diversity audio uplink in the future I hope.

OK, heres what was wrong with the last prototype board...

The 1st thing to go was the debugger from VER1 ! it was a stupid idea to begin with :) I got the tag connect cable in the post and got using it right away ! SWD 6pin connector footprint on bottom right of board in pic above. The on board debugger did work well and had some nice flashing but it was just a wast of space ! I made quite a few errors on routing the pins from the STMF0 -> STM32f7 on the old board and that was fixed with a couple of bodge wires. the worst mistake was with the USB enumeration 1.5k resistor though. it was in series instead of pulling the DP line high. Also the resistor divider was wrong ! somehow I was using 100k instead of 10k. To be fair I didn't have a clue what at the time what USB enumeration was, I was just cobbling together whatever I could understand from the STMF7 discovery board schematic. the next best bit was that I had forgotten that i would need to flash the dubugger itself with STM-link firmware of some kind and had no pins for this ! so it was great fun taking on bodge wires to write the firmware! In the end it all worked and then I thought ... what a waste of board space :) 

my next favourite mistake was the complete misunderstanding of the uSD populated switch. it really is just a switch with 2 pins. for some time saving reason I thought surely the switch pin just goes high when you insert a card. NO! the mechanical switch just bridges the 2 pins so you need to pull the line high with a resistor when connected or something similar.

 WRONG!!! this just does nothing :)

Hopefully better !

insert the card and the detect line goes high through a 10k resistor. Do I need a week resistor to pull line low when no card is inserted so the detect pin is not floating on the ARM ? I'm hoping there is a week resistor in built on GPO pins for that!

Next favourite mistake , I had the Soft Start SS pin grounded and even more stupidly a second 3.3v power supply for the debugger. mmmm. It was one of those really hard to find shorts and hard to fix. I had to get a mini drill and cut the trace right next to the power IC.

This one was a pain to find. The 150pf cap should bridge PLLFILT and PVDD and not be in line with R10 !

Overall the new board quality seams A1 to me. I'm using the smallest drill hole sizes allowable for the vias and in many places i'm down to 6mil track spacing.

Most of the IC pads are 0.5mm which is pretty close!

I've been using PCBWAY.com mostly for my boards and sending them to Japan tax free. They don't charge import tax on electronics here on anything under 100$ value. 

Theres one bad review on EEVBLOG about pcbway but I have never had any issues whatsoever ! They are super helpful in pointing out design mistake when I get a via to near something or have cutout marks that are just wrong daving me time and money. I have tried other PCB company's but I find PCBWAY to be the fastest cheapest and trouble free. I have uploaded project from both Kicad and Altium software and never had issues.

heres some basic point worth knowing and that have saved me quite a lot of money! In fact usually I end up paying more for shipping than the pcb !

PCB prototype service - Only $5 for 10 PCBs and every new member will get a $5 bonus. + Express 24 hour / 48 hour service

I have never used the stencil service or the pick n place service but I will try it one day.

Stencil + Flex PCBs + PCB layout service - 

https://www.pcbway.com/stencil.aspx

This looks really cool although I have not tried it ! Non-profit sponsorship / Crowdfunding project sponsorship - https://www.pcbway.com/project/sponsor/

Share open source projects to get commission? looks great to me ! https://www.pcbway.com/project/shareproject/techshare.aspx

PCB Design Contest -https://www.pcbway.com/project/PCB_DESIGN_CONTEST.aspx

Invite friends and earn money - Send the referral link to your friends, and your friends will get $5 of New User Free Credit. You will receive $20 discount coupon for each friend that have prepaid ,You will also earn 10% of what they (1st order) spends cash.- https://www.pcbway.com/member/specials/invite.aspx

Special features - Real-time fabrication status

Christmas coupons

https://www.pcbway.com/activity/christmascoupons.aspx

I even got some pretty cool looking father christmas PCB's which helped my christmas tree HAHA

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