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Re: Connecting Raspberry Pi to FT-818nd CAT port


 

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Hi folks,

A quick update.? Thanks to all for the various morsels of wisdom.? They were all helpful.?

To document this for others:

1.? Connected the output of the Pi serial Transmit line (aka GPIO14) directly to the FT-818nd Accessory Rx D pin
2.? Connected the output of the FT-818 Tx D through a resistor divider (5k + 10k), and fed the junction to the Pi serial Receive line (aka GPIO15).
3.? Connected the two systems grounds
4.? Enabled the serial port and disabled the serial console in the Pi Configuration "Interfaces" tab

I found author "4x1md" on GitHub, and the software "ft817_cat_python".? Changed the serial port string to /dev/ttyS0 (this is a Pi3B), and it ran with no further changes required.??

For the curious, the project here is to display the frequency of the Pi on my car's in-dash display (where the back-up camera goes).? I can't easily see what I'm tuned to while driving, as the radio is mounted sideways on the passenger-side of the center console, but the dash display is big and easy to see.? I can change frequencies and flip through memory channels by touch, but not read the rig's display.? So, VGA output from the Pi goes to the video in, via an A/B switch for the backup camera.? The Pi also runs Direwolf and YAAC for APRS Packet, or I just do voice on one of several local repeaters.? Really trying not to get the two modes mixed up.

Next step is to do some formatting of the status text and to present it in a GUI box on the screen, auto-launched when booting.

Thanks again to all!

Greg? KO6TH


'David Leckie' djcleckie@... [FT817] wrote:

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Hi

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Slightly ¡°off topic¡± as its not directly RPi related just FT 817 but it might give you some ideas.

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Google IK1ZYW Keypad

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Its about connecting a Atmel ATtiny2313-20PU to a FT 817 to make a custom keypad.

Some good advice about voltage levels etc.

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73

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Dave

GM4NFI

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From: FT817@... [mailto:FT817@...]
Sent: 04 June 2019 12:38 AM
To: ft-817
Subject: [FT817] Connecting Raspberry Pi to FT-818nd CAT port

?

?

Hi folks,

This should be easy to find, but I've not located the details...

I'm looking to connect the serial port of a Raspberry Pi (GPIO14 & 15)
to the CAT port on my FT-818nd. Neither the Pi nor the 818 have RS-232
levels; both are "TTL-ish", I think. It seems silly to buy a CT-62 for
the 818, and a Serial dongle for the Pi, if instead I can simply wire
the two together.

So my questions:

1. Are both ports voltage compatible (3.3v for the Pi, for example)?
2. Is the signaling correct (vs being inverted)?

Thanks!

Greg KO6TH


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