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Posts: 544
Registered: ‎10-12-2004

VCPXpress: Want to make your USB MCU look like a COM Port?

[ Edited ]

Hi all,

 

With the EFM8 launch, we've released VCPXpress, which is a firmware library that enables a USB MCU to communicate with the CP210x Virtual COM Port (VCP) driver.  VCPXpress is built on top of the USB Peripheral Driver and is currently supported on the EFM8 products (EFM8UB), and the CP210x VCP driver is supported on Windows, Mac, and Linux.

 

Software Examples (under USB) and Demos of the VCPXpress library are available with Simplicity Studio v3 - www.silabs.com/simplicity-studio.

 

~Tabi

Tabitha Parker
Senior Manager of MCU and Micrium Applications
Silicon Laboratories
<a href="http://community.silabs.com/t5/Welcome-and-Announcements/Community-Ranking-System-and-Recognition-Program/m-p/140490#U140490"><font color="#000000"><font size="2">Hero</font></font> </a> jmg
Posts: 1,175
Registered: ‎04-27-2004

Re: VCPXpress: Want to make your USB MCU look like a COM Port?

A great idea - Can you give the current code size reports for this library ?

Last reports had it just a little too big for the 8K, needing the 16K part.

Posts: 544
Registered: ‎10-12-2004

Re: VCPXpress: Want to make your USB MCU look like a COM Port?

Hi JMG,

 

Building the basic example (VCPXpress_Echo) for the EFM8UB1 devices is 8920 bytes.  This does not include any extra code for serial interfaces or visualizations on the Memory LCD, so it's about as bare-bones as it can get.  You would need at least the 16 KB EFM8UB1 device in order to use the library.

 

~Tabi

Tabitha Parker
Senior Manager of MCU and Micrium Applications
Silicon Laboratories
Posts: 9
Registered: ‎10-15-2008

Re: VCPXpress: Want to make your USB MCU look like a COM Port?

Dear Tabi,

Thanks for the USB VCP implement on the EFM8 micro.

we also test it on the EFM8UB2 Starter kit, we test the EFM8UB2_VCPXpress_Echo project on the kit.

basically it works. it can operate well when we connect the port and tried sending some words, it can echo back correctly.

anyway, when keep the COM port connected, the PC (XP or win7 O/S) will not able to enter the standby mode.

but when we test a normal VCOM port on the CP2102 cable, no this issue.

 

that's, when insert the EFM8UB2 VCP cable with EFM8UB2_VCPXpress_Echo running, and keep that COM port connected(occupied by any COM program), the PC will not enter standby mode correctly, we need to remove the cable from the USB port, then the PC will back to normal;

or, if the EFM8UB2 insert to the PC USB port, but the corresponding port is not used by any program, then the PC is also normal and will enter standby mode correctly, and also can restore from the standby mode;

 

so I want to know how to solve this issue?

I want to let the EFM8 to simulate a virtual COM at any time and the PC can operates as normal with/without the EFM8 USB VCP COM port connected; and when the PC wake up from  standby mode, the connected COM port can continue to work.

 

is this possible?

Thanks in advance.

Shaowei

 

 

 

 

 

Posts: 9
Registered: ‎10-15-2008

Re: VCPXpress: Want to make your USB MCU look like a COM Port?

Hi, all,

is there anyone can have the solution to bring the EFM8 CDC stack to work with PC well?

that is, it can work with a PC, when that simulated CDC COM port being occupied by a serial program, the PC can still go to standby mode as normal, and can quit from standby mode as normal?

 

as I mentioned in above message, currently when a EFM8 device built based on the demo EFM8UB2_VCPXpress USB stack, when it insert to a PC USB port, and let any serial program to use that COM port, then the PC will NOT be able to enter standby mode.

 

Thanks in advance.

 

B/R,

Shaowei