USB to TTL Basics

[rahlquist]

Hello,

Quite a few people have reported problems and been unable to determine if their Pine was functional or not. The easisest way to monitor your pine is with a USB to TTL serial adapter. There are many types of these for PC's on MAC I am unsure but if someone has knowledge in that are please post and we will try to get a Mod to sticky this. 

Things you will need. A PC. A terminal program able to access COM ports and a USB to TTL adapter for 3.3V. Cables and wires needed to hook it all up. 

Things to look for CH340 ( http://www.ebay.com/itm/USB-To-RS232-TTL...Sw5IJWgmPc ) is what I am currently using. It has drivers from Windows XP through Windows 10 I believe. 

I have also in the past used a FTDI232RL ( http://www.ebay.com/itm/FT232RL-3-3V-5-5...SwrklVMjIp ) which also has lots of drivers available. There a many adapters out there that only support XP through Windows 7 so pay attention to what others you buy. If unsure ask here and hopefully someone will know if it will work.

Connect your serial adapter of choice to your pc and get the drivers setup. When you are done you should be able to find the device in device manager and it will tell you what COM port it is associated with. 

Whatever solution you choose you need to make 3 connections to the pine. These are hooked up in this manner.
RX on FTDI/CH340 to pin 7 on EXP connector
TX on FTDI/CH340 to pin 8 on EXP connector
Gnd on FTDI/CH340 to pin 6 on EXP connector

I use Putty for a terminal program I set it to connect to COM4 and set the baud rate to 115200 and connect. 

Then power up the Pine, you should be watching text fly by. If you are troubleshooting after the boot stops read through the scrollback and find where it mentions errors, you can copy/paste them here or if you are grabbing more than say 20 lines use http://pastebin.com and post the link here along with your issue. 

A few pcitures. http://imgur.com/a/vKl6j

I am attaching a boot log to show you what the output is like.

Sorry if this is a bit rough but wanted to get it posted during my lunch hour. I am thick skinned and open to any comments, suggestions, additions, criticisms etc. So speak up.  As far as I am concerned we are always learning, there is nobody who knows it all in tech.

[tkaiser]

I can recommend also this one: http://www.ebay.com/itm/400565980256

Ordered 5 a while ago and got them within 3 weeks (yeah, that's the problem)

[tllim]

I can recommend also this one: http://www.ebay.com/itm/400565980256

Ordered 5 a while ago and got them within 3 weeks (yeah, that's the problem)

Good suggestion, thanks.

[VeeKayB1]

No relationship to me...

Would this work?  It is from a USA location so faster shipping. 
http://www.ebay.com/itm/3PCS-USB-To-RS23...SwYIhWlmrB

Cheap wires too.

http://www.ebay.com/itm/40pc-Dupont-Wire...SwoQ1Tm8mJ

[DaveyDarko]

I've use CP2102 based, CH340 based, and a PL2303HX based USB to TTL adapters on my Pine64 and other SBCs. All of them I have purchased from Aliexpress for less than $2 shipped. All work.

One thing to consider when using USB-TLL adapters is to make sure you are using the correct voltage adapter. Some are 5v some are 3.3v and some are jumper selectable. One of the UARTs on the Pine64 has protection on the RX if you happen to use a 5v USB to TTL adapter, I don't remember which one, I think it is the on on the EXP connector. Many other SBCs do not have this protection so just make sure you use the right TTL voltage otherwise you might damage your SBC.

[rahlquist]

No relationship to me...

Would this work?  It is from a USA location so faster shipping. 
http://www.ebay.com/itm/3PCS-USB-To-RS23...SwYIhWlmrB

Cheap wires too.

http://www.ebay.com/itm/40pc-Dupont-Wire...SwoQ1Tm8mJ

While I cant promise 100%, yes that looks to be the one I use. Just make sure if you get that one when you get it that the jumper is on the 3.3v setting. The Pine may work with the 5v signal but why chance it.

The name on that auction looked familiar, I bought dupont cables from that user in January of 2015. I left him good feedback so he may be safe to buy from

[xmasone]

Can I just cut the ends off a serial cable and connect it to my serial port?

[rahlquist]

It may work but since most PC serial ports I believe are 5v I dont know if its a good idea. Someone more familiar with the Pine hardware would have to answer that.

[DaveyDarko]

I wound not attempt it, RS232 voltage can swing between -13v to +13v, where as TTL voltage swings between 0v to 3.3v(or 5v if using 5v TTL).

Read here for more info about the difference: https://www.sparkfun.com/tutorials/215

For less that $2 shipped you can get one that works from Aliexpress if cost is an issue.