I'm considering Teensy 3.5 for next work project. Am I OK doing this?

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grease_lighting

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I'm building another 'tester' so I have a few questions to make sure I'm off on the right path before I get too deep. I've chosen the T3.5 as it is 5v tolerant and has a lot of I/O's to control all aspects of my fixture. After my last 'quick and easy' with Arduino Pro Mini's, I'm ready to swear them off for good as they are woefully lacking in program space.

For this project I'm planning on using Serial 4, 5 & 6 due to ease of wiring access. Are they use able by starting out with SerialBegin4? Is it OK to skip 1 & 2?

I'm also planning on using an RA8875 based display. I've read about its mis-behavin data output. For simplicity I was wondering if it really has to be used? I'm not planning on doing screen reads nor am I using the additional GPIO ports or SD Card access. I am also under the impression that the available touch screen controllers either resistive or capacitive would behave well on the SPI bus. Do they use their own controller? Since I've never used them in a design, which works better?

Thanks a bunch.
 
The RX6/TX6 for Serial6 aren't as easy to wire up as the pins for Serial1..Serial5, since you have to solder wires to two pads underneath the Teensy. There are some PCBs that make it easier to wire the pads underneath the Teensy

If you are expecting to do a lot of I/O to your serial UARTs, you want to use Serial1 and Serial2, since these UARTs have an 8 byte hardware FIFO that reduces the need for interrupting the Teensy:

If you are enabling hardware flow control using CTS and RTS, note that Serial4 does not support CTS, while the other serial UARTs have fixed pins for CTS.

You could use the alternate pins for TX1/RX1 of 5/21 or 26/27.
 
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Thank you Michael.

I'm avoiding Serial 1 & 2 as I've routed the SPI signals in the center of the T3.5 towards that end. Use of Serial2 was prohibited by my use of a WIZ820 or 850 ethernet adapter to talk to my device and an SD Card for data logging. Just not using the one on the Buy Display LCD as it has been deemed un-useable by members of this group. Serial 4, 5 & 6 are available at the other end making fanout easy for me. I have written a simple TTY routine to handle the short (<100 characters) messages from some of my target devices. I'm also using quite a few of the pins on the digital side to control my test logic stuff as well as using the FTM's as counters to measure timing delays.

I'm not using any flow control on the serial ports.

I use Mill Max Pogo's (0914-3-15-20-77-14-11-0) from Mouser to connect to the underside pads. The peripheral sockets and pin headers are Samtec. The pin headers have enough grip to keep the pogo's in good contact with the TEENSY board pads. I can gently pry the assembly apart if I have to. I have access to a LPKF Protomat S103 to make my boards. Kind of coarse but I have good success with it.
TEENSY_PCB.png
 
Re the RA8875: Are you planning to use a library or write your own code?

The MISO pin is used for reading status register also, not just data. If you're writing your own code, you could probably get away without using it (albeit maybe not with the most optimum performance but OK for most projects). If you're using a pre-existing lib, it really depends whether that lib relies upon having it.

All that said, the problem with the MISO pin is that it doesn't tri-state when not in use, so you cannot directly connect it to the MISO of another slave device without fear of smoke. But if you're using a dedicated SPI bus just for the RA8875 (i.e. there are no other SPI devices on that SPI bus) you can use the MISO without any worries.

One of my projects uses RA8875 on a dedicated SPI bus. It works absolutely fine.
 
Appreciate the help MUNDUNGUS.

I had read thru the info on the RA8875 not properly tri-stating when in SPI mode. I wanted to avoid having the extra buffer and eating a channel to tri-state the data out in SPI mode. I see it can use I2C of 3-wire SPI, but of course I need to find a suitable driver.

I was planning on using the SUMOTOY library for the RA8875. I'm more of a hardware than software guy so I prefer to use things as-is. Is there an SPI library that will handle multiple busses? I was thinking I would have have to change the names to make similar but multiple libraries to do the same task for different ports.
 
I'm afraid I can't answer as to what the Sumotoy library supports. I've not used it myself. Hopefully some else can chip in on that. Hopefully also someone might know whether that lib needs MISO.

Perhaps you can give a bit more detail of your project? It's not clear to me that you have a conflict with pins or busses. Do you have any info about your pin allocation or exactly what peripherals your project needs?
 
Hey Guys, Big News!

I stumbled on a alternative to milling circuitboards. by using the DMP2800( 25um Resolution, and depending on the conductive Ink (copper or silver based you can create even smaller traces).

The Idea I had was the following which I would like to share:

order a thin layer of plastic maybe Teflon or just FR4 around 50um with copper both sides, use some dynamask,
UV cure that then put it under the DMP2800(smallest resolution, 25um) (UV cure the Ink, or heat cure it) then add another layer of dynamask.
heat cure this again and voila, you get the thinnest substrate, (especially good for HF).
you can repeat this on the other side as well.

Device: http://www.fujifilmusa.com/products/industrial_inkjet_printheads/deposition-products/dmp-2800/

do you guys have any experience in this kind of printing with liquids?
they offer copper ink that has a 30% less conductivity than normal copper

here are a few companies that offer inks, that are UV or Heat Curable.

http://copprint.com/

Silver conductive liquid from MG chemicals is 0.2Ohm per inch.

http://www.dupont.com/products-and-...cs/products/inkjet-silver-conductor-inks.html

I am greatly looking forward to your replies!
 
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