Which USB <> Serial Bridge Chip?

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No-one ever got fired for using a chip from FTDI, but there are not cheap. Does anyone have experience, preferably in commercial products, of the following...

 

CH3xx series

PL series chips from Prolific

MCP22xx series from Microchip

CP2xxx series from Silicon Labs

GL8xx from Genesys

 

Chips that are as plug-and-play with modern PCs as possible are to be preferred.

#1 Hardware Problem? https://www.avrfreaks.net/forum/...

#2 Hardware Problem? Read AVR042.

#3 All grounds are not created equal

#4 Have you proved your chip is running at xxMHz?

#5 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand."

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Started using CP2101 back in 2001 ish. That went obsolete but CP2102 has been an excellent replacement and have used it ever since.

 

It took a long time but finally Windows in the guise of Windows 10 has drivers built-in.

 

<edit> A brave man could make his own using ATmega16U2.

 

Last Edited: Sun. Apr 4, 2021 - 08:44 AM
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N.Winterbottom wrote:

<edit> A brave man could make his own using ATmega16U2.

 

At twice the price of the dedicated chip.

#1 Hardware Problem? https://www.avrfreaks.net/forum/...

#2 Hardware Problem? Read AVR042.

#3 All grounds are not created equal

#4 Have you proved your chip is running at xxMHz?

#5 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand."

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Note that newer FTDI chips like the ft231x are significantly cheaper than the old ft232r* chips...

 

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Brian Fairchild wrote:

At twice the price of the dedicated chip.

OK agreed.  So a really brave man chasing the lowest cost would choose an ATmegaAVR or perhaps XMEGA with built-in USB hardware instead of using a separate chip.

 

I only have experience of this on PIC24 where the Microchip Provided USB stack looks like a Generic CDC. So as with CP2102, no driver install is required for Windows10.

 

There is a caveat with this design in that when spending too long at a debugging breakpoint; Windows bombs out your COM port because you've been unresponsive for some time.

 

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N.Winterbottom wrote:
... and have used it ever since.
NRND though with a follow-on in CP2102N.

N.Winterbottom wrote:
It took a long time but finally Windows in the guise of Windows 10 has drivers built-in.
Indeed

 

edit :

WCID arrived with Windows 8; in addition to WinUSB are third party drivers.

WCID Devices · pbatard/libwdi Wiki · GitHub

 


Classic USB Bridges - USB to UART Bridge - Silicon Labs

USBXpress USB Bridges - USB-to-UART bridge controllers - Silicon Labs

Pololu - CP2102N USB-to-Serial Adapter Carrier

 

What is new with Serial in Windows 10 - Microsoft Tech Community - 270855

[1/4 page]

Now devices that report these compatible IDs:

[USB CDC ACM]

… including popular prototyping boards like Arduinos – just work with our built-in driver.

 

"Dare to be naïve." - Buckminster Fuller

Last Edited: Mon. Apr 5, 2021 - 02:36 AM
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N.Winterbottom wrote:
I only have experience of this on PIC24 where the Microchip Provided USB stack looks like a Generic CDC.
Likewise on USB PIC.

Recent USB PIC have ACT with enhanced UART (FBRG, auto-baud); can move functions into a USB PIC from an AVR (advantage of USB MCU over USB UART)

N.Winterbottom wrote:
So as with CP2102, no driver install is required for Windows10.
OEM drivers can enhance Microsoft drivers.

 


p-star-examples/usb-to-serial.X at master · pololu/p-star-examples · GitHub

Pololu - P-Star Programmable Controllers

PIC18F25K50 - Microcontrollers and Processors

Active Clock Tuning - Developer Help

 

USB UARTs - MaxLinear

...

For applications where the USB interface may be disconnected and reconnected while a COM port is still open, MaxLinear provides the XRUSB1 Windows driver that eliminates the need to close the COM port in the host application. 

...

...  and the GPIOs are readily tailored for enhanced functionality. 

...

due to CH340G IC vendor..... | AVR Freaks

XR21x14x Universal Async Receiver Transmitters - MaxLinear | Mouser

 

"Dare to be naïve." - Buckminster Fuller

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Brian Fairchild wrote:

CH3xx series

PL series chips from Prolific

CP2xxx series from Silicon Labs

The CH340 has new version CH343, claiming higher baud rates of 6Mbd   http://special.wch.cn/zh_cn/prod...

 

The PL2303 has newest version as PL2303G series, claims up to 12MBd,  I have some PL2303GS coming from Amazon I'll test this week.  

https://prolificusa.com/product-...

 

The CP2102 is newest as CP2102N, which is a better performer than the CP2102, tho many Asian boards still use CP2102.

Silabs also have a EFM8UB3 48MHz 40k Flash mcu, that can host a USB-Serial 

 

Also good, but hard to get, is the  EXAR  XR21V1410 which can set up to 12MBd

 

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an important criterion for selecting a device may be the ability to have unique USB serial numbers if multiple devices are in use. On the CP2102 you can program your own serial number, the CH340 is not programmable and has no unique serial number. 

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PL2303, and FT230RL have both been cloned to the point where vendors have stopped supporting some versions (PL23xx) and/or specifically included code that detects clones and performs badly or not at all (FT232R)...  I'm somewhat inclined to avoid them for that reason :-(

 

I like CH340E MODULES from Aliexpress - USB/Serial chip, USB connector, and a couple of LEDs, all in a tiny, cheap module.   But I'm not sure I consider the supply "stable" enough to put on a commercial product.  (My favorite Aliexpress vendor seems to have abandoned "less reliable" shipping, which means that their cheapest shipping option is now about $50...  :-( )

 

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Who-me wrote:
The CH340 has new version CH343, claiming higher baud rates of 6Mbd
4 Mbps for CH9102

USB - NanjingQinhengMicroelectronics (WCH)

due to

Trying out the WCH CH9102F in place of a CP2102N - YouTube (Adafruit Industries, 55s)

CH9102F | USB ICs | Interface ICs |LCSC.com - LCSC.COM

 

"Dare to be naïve." - Buckminster Fuller

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gchapman wrote:

Who-me wrote:
The CH340 has new version CH343, claiming higher baud rates of 6Mbd
4 Mbps for CH9102

USB - NanjingQinhengMicroelectronics (WCH)

due to

Trying out the WCH CH9102F in place of a CP2102N - YouTube (Adafruit Industries, 55s)

CH9102F | USB ICs | Interface ICs |LCSC.com - LCSC.COM

 

 

I got some of those a few weeks back, below are my test notes 

- Not as granular as a CP2102N, which supports 24M/N

- Full handshake was not testable, as the low cost board, lacks full pin mapping :( 

- 6Mbd is valid, but looks to need care. If you really need that much maybe a FT232H is better choice.   

- Driver and chip handing of some off-valid points is erratic and poor. Unexpected baud values or lockups occur. If you stick to 'known good' values, you are ok. CP2102N is cleaner, it gives nearest? valid baud 

 

 

 ~~~~~~~~~~~~~~~~~~~~~~~~~ WCH CH9102 ~~~~~~~~~~~~~~~~~~~~~~~~  Hmm Web Download is : 8/05/2021 1.3.2021.5 but Win Update finds 8/08/2021 1.5.2021.8
 pin labeled RXD is actually UART.TX
 IO0 is RTS OR DTR - ie merges the two signals.
 IO2 is ??  seems floating just bridged 2 connectors not CTS or any handshake signal ??
 Looks to support 6MBd/N plus 4MBd,921600,307200.
 Values off those solution are unpredictable : most snap, some do 50 baud, some fail.
 921600 307200  need exact define, as they seem to be special handled in SW

 Loopback   BAUD : Counter values - ideal is Counter = Baud/2,  Errors are from 6M/N, not from nominal baud
 115200  6M/52 = 115385  = -0.0633%
 250k   124.8875k  = -0.0900%
 6M/19.5 = 307692 153.714k = -0.085% but MUST ask for 307200 as special case tested, else snaps to 6M/20 -2.570% error
 500k   249.6997   = -0.120%
 545454 272.6168k  = -0.0404%
 600k   299.6991   = -0.10%
 666667 333.029k   = -0.091%
 705882 330.061k   << snaps to 666667 12M/17
 857143 428.143k   = -0.1000%
 1MBd   499.487kHz = -0.1027%
 921600  6M/6.5 = 923077  100*(1-923076/(461.218k*2)) = -0.06938% but MUST ask for 921600 as special case tested, else snaps to 6M/14
 1.090909M -> oops sends at 25.011Hz so 50 baud ?!?  WTF
 1.2Md  599.203kHz
 1.33333MBd  599.138k so snaps to 1.2MBd ?     24M/18 = 1333333 or 12M /9 so missing 1.333MBd is poor
 1.5Mbd 748.942k
 2MBd   998.201k
 3Mbd   1.459M
 4MBd   1.879768M  see 240us bursts with gaps of 40us - a strange 240u/(10/4M) = 96 chars ?  Smallest seen is 80us or 32 char blocks.
 6Mbd   2.3818M    same 32 char blocks  53.420u/(10/6M) - looks a little slow at 6MBd  - this is 4.763600 average duplex sustained, 9.53mbd
 above 6MBd fails to apply baud
 4.8MBd fails to send anything, locks up also fails to receive anything from remote

 Strange at 6MBd 6899936 vs 6900000, dropped 64 but always about 7M chars ?
 15300000-15299680 = 320 - not seeing RTS ? Hmm if make DTR Green does that help ?
 see 150M chars no errors, and some pulses on RTS - try to catch RTS whefRTCn it drops chars ?

CH9102.TX only is
 3Mbd  1491.115k  100*(1-3M/(1491.135k*2)) = -0.594% slow - some gaps appearing,
 4Mbd  1.962 100*(1-4M/(1962.168k*2))      = 98.072% sustained average.
 6MBd  100+100*(1-6M/(2796.764k*2))        = 92.733% sustained average.

Note slew rate at 6MBd is a tad marginal, not sure if PCB design or device itself.
  FT232H <-> CH9102
        6MBd ->   OK at 384 bytes ok at 769 bytes ok at 1024 ok at 300k one way only. impressive RX speeds
 6MB burst duplex, seems to have correct char count, but 9102.TX -> 232H.RX has errors in chars  0xD5 replaces some 0x55 ?

 

 

Also from WCH, I notice their new RISC V core 144MHz part claims USB-HS and the CH32V305FPB6 is a TSSOP20 version.

I'd be curious how that works as a better USB Bridge ? - but seems too new to be tested yet ?  LCSC does have eval boards of the bigger variants. 

 

Last Edited: Tue. May 3, 2022 - 02:20 AM
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Who-me wrote:
- Not as granular as a CP2102N, which supports 24M/N
Forgot that CP2102N has a clock output of 24 MHz / N (handy for AVRxt until AVR DU)

Who-me wrote:
Also from WCH, I notice their new RISC V core 144MHz part claims USB-HS ... LCSC does have eval boards of the bigger variants. 
Ethernet MAC too with a board on Tindie (context is terminal server with 8 UART)

 


cp2102n-datasheet.pdf (Pololu)

[bottom of page 20]

4.3.6 Clock Output (CLK)

An optional clock output is available on CP2102N devices.

FCLK = 48 MHz / 2 × N

The valid values for N are 1 to 256.

Note: The clock output stops and is no longer present on the pin when the CP2102N device is in USB Suspend. This occurs when the device is connected to USB and the host controller suspends the device (either through a feature like Selective Suspend or when the host PC is in Hibernate or Sleep modes) or when the CP2102N is disconnected from the host in self-powered mode.

AVR DU | AVR Freaks

 

RISC-V CH32V307 QuickStart E01 | WCH - RISC-V International

GitHub - openwch/ch32v307: Including the SDK、HDK、Datasheet of RISC-V MCU CH32V307 and other relevant development materials

WCH CH32V307 RISC-V development board features 8 UART ports controlled over Ethernet - CNX Software

WCH CH32V307 RISC-V development board 8 UART ports from Maker go on Tindie

 

"Dare to be naïve." - Buckminster Fuller

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My TI boards come with CP2xxx series from Silicon Labs.

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The CPs and CHs appears at numberous kits nowadays.The FTDIs seems in competition.

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