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Socketing a Nano to the other side of the Raduino

Jerry Gaffke
 

We would like to socket the Nano, but then the standard display doesn't fit,
If we extend the pins to make it fit, then we may have to redo our enclosure
to give the display some extra room.

Here's a possible solution:

Remove Nano from the Raduino, add socket strips to the other side of the Raduino,
Get a Nano with the pins not yet installed:
    https://www.amazon.com/Elegoo-Arduino-ATmega328P-without-compatible/dp/B0713XK923
Solder them pins to the top side of the Nano.
Plug and play.

Bad news is that the Nano is now sitting right above the RF part of the uBitx,
no longer shielded by the Raduino's ground plane.
So the audio tone issue could be the next issue to solve.

Fortunately, the CH340 is now easy to remove/disable, use a USB-to-UART cable assembly instead.

Perhaps hang caps on the 16mhz resonator to bring it down in frequency,
or replace it with a non-16mhz crystal?  Drive it from the BFO?

Or tinfoil and duct tape?

Jerry, KE7ER

ajparent1/KB1GMX <kb1gmx@...>
 

Why not remote it some from the mainboard and put a box around the back of it
with the wires sneaking out of  it.  The front of the box is the front panel and the
Raduino is tinned up.  Take care with the signal leads (use SHORT twisted pairs).
Used those tricks for old style counter circuits that radiated digital noise like mad.

In my case the height of the board when mounted is a problem.  Solution is change
the board connector into a right angle and then relocate the display with wires.
That lowers the profile.   Both boards can easily then have a cover over them
made of soldered up PCB, hobby brass, or copper screening.  Control pins will
exit though the screen box via 1000pf feedthroughs.  I try to keep noise in
the box so to speak.

Allison

Kees T
 

You could actually have different Nanos for different overall functions and just swap them out since it would be pluggable.

73 Kees K5BCQ

Jerry Gaffke
 

Cuz sheet metal work is not as much fun as burning solder.

Shielding various sections of the radio from each other is not a bad idea.
And the Raduino/display is a good place to start.

Allowing the Si5351 clocks out of the box while disallowing
everything else might be problematic.
Simple solution: move the Si5351 to the uBitx, filter the i2c bus to a few hundred khz and less.

Though I do think that running the processor from the BFO and kicking 
the USB-to-UART out entirely would pretty well solve most interference
from the Raduino.  

Jerry



On Mon, May 21, 2018 at 07:23 pm, ajparent1/KB1GMX wrote:
Why not remote it some from the mainboard and put a box around the back of it
with the wires sneaking out of  it.  The front of the box is the front panel and the
Raduino is tinned up.  Take care with the signal leads (use SHORT twisted pairs).
Used those tricks for old style counter circuits that radiated digital noise like mad.

Rod Davis
 

Allison and all,

with the KD8CEC firmware you can opt for a I2C display
connection; the display can be remote quite some distance
with just 2 wires (plus power and ground).

Rod KM6SN



On 05/21/2018 07:23 PM, ajparent1/KB1GMX wrote:
Why not remote it some from the mainboard and put a box around the back of it
with the wires sneaking out of  it.  The front of the box is the front panel and the
Raduino is tinned up.  Take care with the signal leads (use SHORT twisted pairs).
Used those tricks for old style counter circuits that radiated digital noise like mad.

In my case the height of the board when mounted is a problem.  Solution is change
the board connector into a right angle and then relocate the display with wires.
That lowers the profile.   Both boards can easily then have a cover over them
made of soldered up PCB, hobby brass, or copper screening.  Control pins will
exit though the screen box via 1000pf feedthroughs.  I try to keep noise in
the box so to speak.

Allison

Jack, W8TEE
 

Some displays might be configured to work with the SPI interface, too.

Jack, W8TEE

On Tuesday, May 22, 2018, 7:22:37 AM EDT, Rod Davis <km6sn@...> wrote:


Allison and all,

with the KD8CEC firmware you can opt for a I2C display
connection; the display can be remote quite some distance
with just 2 wires (plus power and ground).

Rod KM6SN



On 05/21/2018 07:23 PM, ajparent1/KB1GMX wrote:
Why not remote it some from the mainboard and put a box around the back of it
with the wires sneaking out of  it.  The front of the box is the front panel and the
Raduino is tinned up.  Take care with the signal leads (use SHORT twisted pairs).
Used those tricks for old style counter circuits that radiated digital noise like mad.

In my case the height of the board when mounted is a problem.  Solution is change
the board connector into a right angle and then relocate the display with wires.
That lowers the profile.   Both boards can easily then have a cover over them
made of soldered up PCB, hobby brass, or copper screening.  Control pins will
exit though the screen box via 1000pf feedthroughs.  I try to keep noise in
the box so to speak.

Allison

Jerry Gaffke
 

I butchered mine, have the Nano socketed into the back of the Raduino as suggested,
hanging over the radio.  Works fine, and no mechanical conflicts.  Not much RFI either.

Difficult to cut the old Nano free using diagonal cutters, I wound up shredding the Nano
into tiny little pieces.  Maybe better to use a Dremel tool using a mini angle grinder:
    https://www.dremel.com/en_US/accessories-and-attachments/-/subcategory/accessory/find-by-tool/27343/rotary/27382
Then remove what's left on the black plastic from that header  and pluck the pins out from that
black plastic side of the board while heating them one at a time with a soldering iron.
Don't pull the cut side of the pin through the board, the ragged ends of the pins where they
were cut will rip up the pads.

Clean the board well with alcohol when done, a little bit of metalic grit in the wrong place
will cause big trouble.

LED's on the Nano are no longer visible, but I seldom look for them.  Only need them when
programming, and even then not much.  And since the Nano is socketed, you can pop
the Nano out of there when programming and get full access if you wish.
This also gives access to the reset switch, though the reset comes out to that unused
6 pin programming header on one end of the Nano, could add a second reset switch there.

Here's a schematic of the Chinese Nano Clones:
    http://actrl.cz/blog/wp-content/uploads/nano_ch340_schematics-rev1.pdf

With the USB cable from the host not plugged into the Nano, I see no 12mhz 
on the CH340's resonator.  When a USB cable is plugged in, I see 5v pk-pk there, would 
expect that to be causing all sorts of havoc.

But curiously enough, only a very faint raspy little bird, in my case around 12.05mhz.
That can vary by 100khz from the nominal 12mhz, as the ceramic resonators are not
very accurate.  Not much evidence of the dreaded 16mhz oscillator either, just a
very faint bird when tuning around without an antenna.  Signals from those 12
and 16mhz resonators can be identified by bringing your finger near the resonator,
the frequency will change by several khz.  Since the 16mhz resonator is now hidden,
I brought a wire out from the ATMega328P pin 8 (TOSC2, drives the resonator) where
I could touch it.  Under one volt pk-pk there, the Nano is apparently programmed to use
the low power oscillator. 

But lots of other birdies, strong and pure, clearly heard with an antenna connected,
and clearly harmonics of something since they zip by much faster than I am tuning.
These don't move when I put my finger on the Nano's resonators, I haven't tried to 
identify exactly where they are coming from.
The (minor) downside of an unshielded radio that doesn't bother with the extra $100 of sheet metal. 
And of course, I can hear the BFO quite well too. 

Would be very interesting to get one of those Nano's that was 
creating all the obnoxious audio tones, see exactly what's going on.  A possible fix might
be to program the Nano to use the internal RC oscillator instead of the 12mhz 
resonator.  Factory default for the Atmel chip is around 8mhz using the RC oscillator,
this can be trimmed to most anything you want via flash bits.

Here's the Atmel datasheet:
  http://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-8271-8-bit-AVR-Microcontroller-ATmega48A-48PA-88A-88PA-168A-168PA-328-328P_datasheet_Complete.pdf




##########
Programming the Nano through a CP2102 instead of the onboard CH340:

The 12mhz CH340 resonator may not be an issue, it's disabled when no cable to the host is plugged
into the Nano's mini-USB port, and even when plugged in I didn't hear much of it when tuning the radio
around 12mhz.  However, I was able to verify that a CP2102 adapter such as this:
    http://www.oddwires.com/cp2102-serial-adapter-module-usb-to-rs232-with-jumper-wires/
worked fine with the Nano under the Arduino IDE.  So I'll document that here in case it's of interest:

The Nano's CH340 has series 1k resistors on the TXD and RXD UART lines to the ATMega328P's D0,D1. 
So when the CH340 is not plugged into a USB host and is quiet, we can drive D0,D1 from the external CP2102.   
Hookup is as follows: 
CP2102 GND to Nano GND
CP2102 5v to Nano 5v
CP2102 RXD to Nano TXD (D0)
CP2102 TXD to Nano RXD (D1)

The 5v pin from the CP2102 is there to supply power to our Nano, about 100ma max I believe.
The 3.3v pin from the CP2102 is there to provide 3.3v if you need it, we don't.
The CP2102 chip from SiLabs runs on 3.3v, and so drives TXD to a max of 3.3v
but that is sufficient to work with the RXD input of our 5v Nano.
The CP2102 chip has 5v tolerant inputs, so the 5v TXD from the Nano is perfectly fine.

Verify that your operating system sees the CP2102, and select the correct port within the Arduino IDE.
(Doing that was trivial under Ubuntu, but you and google are on your own here.)
Hold the Nano reset button down, click Upload in the Nano IDE, wait till the compile is complete, release the button.
Should just load exactly as it did with the CH340.

You can avoid messing with the Nano's reset button if you hook the CP2012 DTR line to one of
the RST pins on the Nano through a series capacitor.  The cap is typically 0.1uF, but I found that not to be
sufficient, probably because the 0.1uF cap to the CH340 on the Nano was sucking away much of the DTR's
attempt at reset.  Bumping that series cap in the DTR from the CP2102 up to a 3.3uF cap worked for me.

You could also use one of the very popular FTDI cables in a similar manner.
Try to get a real one, avoid the clones, as FTDI is now engaging in defensive driver writing, disabling any clones it sees.
They got tired of most calls to their product support team turning out to be a problem with a clone.
I'm speaking here of devices that pretend to be an FTDI chip, the CH340 is not an FTDI clone.
#########

Jerry, KE7ER


 

Jerry Gaffke
 

Might be able to dampen those birdies by fiddling with si5351 output drive levels,
which determines how hard the diode mixers are driven.

It's also possible these birdies are due in part to crosstalk between the three clocks
coming out of the si5351.   (Which would be affected by the drive level selected.)
If so, could be addressed by a better Raduino using something other than a single si5351.  


On Tue, May 22, 2018 at 09:34 am, Jerry Gaffke wrote:
But lots of other birdies, strong and pure, clearly heard with an antenna connected,
and clearly harmonics of something since they zip by much faster than I am tuning.
These don't move when I put my finger on the Nano's resonators, I haven't tried to 
identify exactly where they are coming from.

_Dave_ K0MBT
 

I socketed a nano on my bitx40. Ran the pins out of the top of the nano so it was a straight plug into the sockets coming out of the wrong side of the board. 
No big deal.

Ashhar Farhan
 

The new boards have the arduino socketed on the other sidd.
- f

On Sun, 27 May 2018, 17:46 , <davesters@...> wrote:
I socketed a nano on my bitx40. Ran the pins out of the top of the nano so it was a straight plug into the sockets coming out of the wrong side of the board. 
No big deal.

Jerry Gaffke
 

Good.
Having the Nano socketed will mostly solve a lot of problems.

With the audio connector integrated, the Raduino could incorporate all front panel controls,
with mounting holes for the panels and switches.
Perhaps two boards, the second board *is* the front panel, sized to fit a particular enclosure
such as the Hammond 1455T1601BK extruded aluminum box.

Did the Raduino board layout get changed to move the Nano to the other side?
Or did you move the header pins to the other side of the Nano?
If it's the latter, then people buying spare Nano's should get the ones that don't yet have
the header pins soldered in place.  

>  post 50466:  "I have brought the audio connector in-line with the raduino connector."

I measure roughly 1.64 inches (41.7mm) between pin 16 of the Raduino connector (the last pin)
to pin 1 of the audio connector on the v3 uBitx board.
Has that dimension changed on v4?
Can you give an exact number for that dimension?

Better yet, make the NC drill file for the uBitx available.
Then we would have placement of all mounting holes and connector holes.
Board edges could be inferred from the mounting holes,
though ideally you would give exact distances from those holes to the board edges.

Adding a diode on the 12v line going in and 1k resistors on Nano IO lines leaving the board 
on any re-do of the Raduino would make it far less prone to damage.
 
Given all the changes expected in the power amp, selling the uBitx as an untested
board with only the autostuffed surface mount parts could be fairly popular.

Jerry, KE7ER


On Sun, May 27, 2018 at 05:30 am, Ashhar Farhan wrote:
The new boards have the arduino socketed on the other sidd.
- f