too many options .... rPi serial to ECM how ?

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roscoe
Posts: 35
Joined: Sat Jul 10, 2010 4:53 am

too many options .... rPi serial to ECM how ?

Post by roscoe » Mon Aug 15, 2016 1:09 pm

what is the easy cheapest way to connect these 2 fellows rPi & ECM 1240 together ...

? some kind of serial USB
? or can the rPi serial be connected directly tidily to the rPi ?

just looking to play around with btmon.py
ben
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Joined: Fri Jun 04, 2010 9:39 am

Re: too many options .... rPi serial to ECM how ?

Post by ben » Wed Aug 17, 2016 10:11 am

roscoe wrote:what is the easy cheapest way to connect these 2 fellows rPi & ECM 1240 together ...

? some kind of serial USB
? or can the rPi serial be connected directly tidily to the rPi ?

just looking to play around with btmon.py

Serial-to-USB is likely the easiest, and likely the tidiest as cases for the rPi provide openings for the USB connections.

You could also use a shield like this one here: http://www.seeedstudio.com/Raspberry-Pi ... -2408.html.
Ben
Brultech Research Inc.
E: ben(at)brultech.com
roscoe
Posts: 35
Joined: Sat Jul 10, 2010 4:53 am

Re: too many options .... rPi serial to ECM how ?

Post by roscoe » Thu Aug 18, 2016 2:42 am

thanks Ben,

I was about to reply to my own question....

1. since rPi seems to use 3.3v for serial, it seems Not possible to do a simple RXd/Txd/Gnd direct cable connection, like I use on old laptop. Rather than level shifting it seems much easier to obtain a USB/Serial for a few quid. (not sure what specific one to recommend, there are zillion on ebay)

2. Once the rPi is in a nice case its a pain to connect to the serial port which are not exposed outside the box, so using the USB is easier, also there is no need to reconfigure rPi using console for its serial port.

3. Serial > Ethernet things seem to jump up in price a fair bit & I have rPi I & II models lying around doing nothing.

...then once cable arrives, I'll use one of the various setup guides
https://www.brultech.com/community/view ... =40&t=1578

I plan to just use MQTT to pass data to an Influxdb instance.

(oh can you move this to the Raspberry Pi/SBC area ?)
wci68
Posts: 43
Joined: Thu Dec 17, 2015 4:31 pm

Re: too many options .... rPi serial to ECM how ?

Post by wci68 » Mon Aug 22, 2016 7:00 pm

roscoe wrote:1. since rPi seems to use 3.3v for serial, it seems Not possible to do a simple RXd/Txd/Gnd direct cable connection, like I use on old laptop. Rather than level shifting it seems much easier to obtain a USB/Serial for a few quid. (not sure what specific one to recommend, there are zillion on ebay)

2. Once the rPi is in a nice case its a pain to connect to the serial port which are not exposed outside the box, so using the USB is easier, also there is no need to reconfigure rPi using console for its serial port.

3. Serial > Ethernet things seem to jump up in price a fair bit & I have rPi I & II models lying around doing nothing.
Yes, in general for applications that need to actually use RS232 the preferred solution is to use a USB/serial adapter. Most SBCs provide TTL serial ports rather than targeting RS232.

Sadly, Prolific has seen a considerable amount of counterfeit parts which are generally less-than-reliable. If you can be sure to find a solution with a genuine Prolific chip that would be one recommendation.

FTDI so far has escaped such counterfeit activity mostly (but not entirely) as another recommendation. I currently use a pair of USB/serial converters based on the FTDI 2232H on my rPi2 for my pair of GEMs. I use btmon.py on one of the serial ports of each GEM and configured ser2net on the other serial port to map to IP.

The actual vendor solution is not as important as the bridge chip.
ben
Site Admin
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Joined: Fri Jun 04, 2010 9:39 am

Re: too many options .... rPi serial to ECM how ?

Post by ben » Tue Aug 23, 2016 10:47 am

wci68 wrote: Sadly, Prolific has seen a considerable amount of counterfeit parts which are generally less-than-reliable. If you can be sure to find a solution with a genuine Prolific chip that would be one recommendation.

FTDI so far has escaped such counterfeit activity mostly (but not entirely) as another recommendation. I currently use a pair of USB/serial converters based on the FTDI 2232H on my rPi2 for my pair of GEMs. I use btmon.py on one of the serial ports of each GEM and configured ser2net on the other serial port to map to IP.

The actual vendor solution is not as important as the bridge chip.
We strictly use Silicon Lab-based Serial-to-USB cables because of the problems noted above. The counterfeit Prolific chips have given us issues when it comes to Windows-compatibility with higher-speed data transfer (swapping bytes at random).
Ben
Brultech Research Inc.
E: ben(at)brultech.com
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