Serial Port Enigma

Hi all, In order to run Serial Bus Servos, the manufacturer instructs me to use a Mega 2560 and to install CH34X USB-SERIAL DRIVER. I've installed this driver on my Mac but here's my enigma: When I connect the Mega 2560 this serial port does not show. I only have /dev/cu.usbmodem143201. Using this port gives me avrdude:stk500v2_ReceiveMessage(): timeout error. But if I connect an Arduino Uno, I have: /dev/cu.wchusbserial14320 and /dev/cu.usbserial-14320 Which I can't use since I need the Mega. I'm stuck and confused on what to do, appreciate help.

I don't know anything about Apple PCs. It would probably be a good idea if you edit your Title to mention that this is an Apple Mac problem so you catch the attention of people who can help you. If you edit your Original Post you can change the Title.

...R

Tkx but I don't think it's an Apple Mac problem. What would you think if it was Windows ?

ba47: Tkx but I don't think it's an Apple Mac problem. What would you think if it was Windows ?

You are the person who told us you are using a Mac - what was I supposed to think.

I use Linux, which is probably closer to a Mac than Windows. On Linux I have never needed to install drivers for Arduinos - genuine or clones.

...R

Robin, I just mentioned it to be precise. Maybe I shouldn't have, it could create confusion. In order to run those servos and use the SCservolibrary they want you to install that driver for Windows, Mac or Linux.

ba47:
In order to run those servos and use the SCservolibrary they want you to install that driver for Windows, Mac or Linux.

It would help if you can provide a link to the documentation where they say that. It would not surprise me to find it was written by a Windows geek who hasn’t a clue about Mac or Linux.

And, as I implied in Reply #1, I suspect the fact that you are using a Mac is central to the problem.

…R

Does the Mega have a CH340 usb to TTL interface chip?

Can you please provide some links to the servos you plan to use and the library they require?

Are the servos run by the Mega or directly by the computer?

@catteldog, Maybe you nailed the problem. I just noticed that my Mega is a clone. So, I don’t know if it has CH340 usb to TTL interface chip !?! (that’s over my head). But I notice the fact that with a genuine UNO I do get the port >> /dev/cu.wchusbserial14320 and with clone Mega I don’t have that port.

The servos I have are called serial bus servos, declared that they can be daisy chained, up to hundreds, to their control board, then to Arduino, occupying only 4 pins of Arduino. They can be used in servo or motor mode with position feed back, speed control, temperature feed back, etc. These servos can be controlled by the computer using a debug interface or by Arduino using the SCservolibrary. Unfortunately, I can’t find any good tutorial or documentation. I bought them from FeeTech and have been in contact with them to get them running, but so far NO luck. There’s another company that makes them, Hiwonder, they have some tutorials on Youtube you may want to watch or just google for Serial Bus Servos.
Here’s the link to FeeTech’s serial bus technology:
http://www.feetechrc.com/solution.html

Here’s the specs of the servos I bought:
http://www.feetechrc.com/6v-45kg-magnetic-code-360-degree-serial-bus-steering-gear.html

Here’s the debug/control board:
http://www.feetechrc.com/fe-urt-1-usb转ttl485总线编程器.html

Here’s the driver they ask you to install :

I’m attaching the library and a docx file for their SCS servos (not my servos) just so you can get a better idea.

SCServoArduinoLib.zip (12.6 KB)

oops, won't let me attach the docx file.

Here it is in pdf format

SCS15 ManualEnglish.pdf (1.04 MB)

ba47: Here's the driver they ask you to install : http://www.wch.cn/download/CH341SER_EXE.html

As this is a .EXE file it is clearly intended for Windows.

I can't see anything on the FeeTech website that explains how the serial bus servos are controlled or where they advise you to download the driver.

...R

Robin, you only looked at the first line. Scroll down and you'll see the diver for Linux and Mac.I "can't see anything on the FeeTech website that explains how the serial bus servos are controlled or where they advise you to download the driver." In fact there's no clear instructions, I had to write them and ask.

ba47: Robin, you only looked at the first line. Scroll down

Apologies.

But I don't understand why there is a Linux driver. The Linux Mint running on this laptop connects to every Arduino board I have (genuine and clone) without needing to download any drivers.

What happens if you uninstall the driver you downloaded and then try connecting your Mega?

I still say you need to mention Apple Mac in your title.

...R

It's Not a Mac issue. Some clone Arduinos have have a different serial communication chip than the standard FTDI. https://www.youtube.com/watch?v=Ix4t-_RZ7NI&ab_channel=MKmeLab

Some driver boards that use CH340 chip for Asynchronous serial communication also need these drivers. Sparkfun, for multiple operating systems. https://learn.sparkfun.com/tutorials/how-to-install-ch340-drivers/all

I don't know if it has CH340 usb to TTL interface chip !?!

Many Megas use an Atmel 16U2 as the interface chip, however The CH340 is present on some.

Look near the USB/power connector. You will see a silver can (16MHz cyrstal) and an IC If the ic is small and square it is a 16U2. If it is larger, and longer than wide it may be a ch340.

If you can't figure out what you have, provide a picture of your Mega.

Here's the debug/control board: http://www.feetechrc.com/fe-urt-1-usb%E8%BD%ACttl485%E6%80%BB%E7%BA%BF%E7%BC%96%E7%A8%8B%E5%99%A8.html

That board has a CH340 usb interface chip. To connect that to your computer you will need the CH340 driver.

If you use that control board, does it connect to the Mega or is it stand alone?

cattledog:
That board has a CH340 usb interface chip. To connect that to your computer you will need the CH340 driver.

I have boards on a 3D printer and for a small CNC mill that have CH340 chips and I have not needed to add any drivers to my Linux Mint.

MaxOS (or whatever it is called) is much closer to Linux than to Windows.

…R

Thks cattledog, I’m attaching the photo of the Mega.

They use an UNO in their instructions (please see attachment) but then they told me to use a MEGA.
Their wiring is Tx → Tx and Rx → Rx . I thought that was wrong but they confirm
that’s the right hook up.
So basically that driver is for the board ?
If I use the genuino UNO with port /dev/cu.wchusbserial14320 I get this error :
avrdude: : programmer is not responding
avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x00
or this error :
avrdude: stk500v2_ReceiveMessage():timeout
and If I use the clone MEGA I don’t have that port and won’t work

Sorry, it didn't upload the Mega's photo. Here it is

MEGA.jpg|0x0

The Mega clearly has a 16U2 as the usb/ttl interface chip. It is not a ch340.

So basically that driver is for the board ?

Yes, if you were going to connect the usb from a computer to that interface board it goes through a ch340 chip.

I am a Windows user, have no experience with Macs, and can not add any information as to whether or not you have to load drivers and what is plug and play.

I am not clear as to whether or not you can connect your computer to the UNO or Mega, see as connected, and download a simple test program like Blink. If you can’t then that is your first order of business, and this is all separate and independent from the use of the interface board and the servos.

Once you can connect to the Arduino we can work out the connection and coding with the interface board.