Cypress CY7C65213A-Based RS232 Adapter & Power Supply

[Gandalf_Sr]

This is a continuation of a thread I started here.

The first board I built was too wide (for a standard breadboard) so I shrunk the width, it's now 36 x 21.5 mm.  I also did away with the PTC as it dumped power whenever any load was drawn.

What I ended up with is a CY7C65213A USB-serial adapter, which includes a small power supply (components under the PCB). It is plug and play with many operating systems and enables serial communications with low voltage PCBs using RS232 (ground referenced) voltages as low as 1.7V The power supply section offers 3 (shared ground) supplies of 5V, 3.3V, and 1.7V – 4.2V adjustable.  It's built and tested and I have several spare PCBs.

The small FT232 PCBs that you can get for $5 are OK but they:
a. Can only be used at 5V or 3.3V levels
b. Have very limited power output capability (if any)
c. The really cheap ones from Banggood and Aliexpress have fake FTDI chips on them which can mess up your communications

Design files are in the next post and there's a couple of pictures below.

[Gandalf_Sr]

Here's the design features:
•   Supports RS232/RS422/RS485 interfaces at data rates up to 3 MBps
•   Unique serial number means each device will assign and reserve a COM port for each adapter
•   Compatible with USB 2.0 and USB 3.0 host controllers
•   Driver support for Windows/IOS/Linux/Android - typically plug and play
•   Configurable signals using free USB-Serial Configuration Utility available from Cypress
•   Supports USB battery charging & USB break signal through user-configuration
•   Tx (red) and Rx (orange) LEDs provided for at-a-glance activity indication
•   Power available is 5V@500mA, 3.3V@800 mA, and 1.6V – 4.2V@600mA (within limits of host USB supply)
•   Jumper-selectable input/output voltage (VIO) of 5V, 3.3V, or adjustable using trimmer pot
•   All pins broken out on headers to provide full access including 8 GPIO pins
•   Standard Arduino-style 6-pin connector (J5) provides VIO and Ground as well as DTR
•   Small 0.7” width allows plugging into 0.1” breadboards with 2 spare holes either side
•   Uses reliable micro-USB connector (more reliable than mini-USB connector)
•   Tiny 36 x 21.5 mm board with 3 header connectors

[EDIT1] 4/9/20 Added schematic vn1f and BOM as .pdf
[EDIT2] 4/10/20 Added user guide vn 2 as .pdf

[WattsThat]

Excellent idea and well done, thank you. Let us us know if you have unpopulated boards you want to sell.

[coromonadalix]

Nice board 

Dont want to be a nag, but sparkfun has almost the same design ?? at 13.95$ usd
https://learn.sparkfun.com/tutorials/sparkfun-usb-uart-breakout-cy7c65213-hookup-guide

But yours has the adjustable output

[Gandalf_Sr]

Nice board 

Dont want to be a nag, but sparkfun has almost the same design ?? at 13.95$ usd
https://learn.sparkfun.com/tutorials/sparkfun-usb-uart-breakout-cy7c65213-hookup-guide

But yours has the adjustable output

Interesting, I am not trying to compete with anyone.  I actually screwed up with my PCB order by sending the same Gerbers for what were supposed to be 2 different designs so now I have 200 of my 4-layer ENIG PCBs for this design that I don't need.   PM me if you want any, they will not be free but close.

[perdrix]

Kudos to you sir!

Very interesting - How hard would it be to add support for full RS-232 voltage swings - this would them obviate the need to have lots of different "USB-Serial" adapters - I already have a 3.3V and 5V and full range bipolar RS-232.   I can see that having a "Universal USB-Serial" adapter would be excellent.  Maybe just need to add some charge pumps?

David

[Gandalf_Sr]

Kudos to you sir!

Very interesting - How hard would it be to add support for full RS-232 voltage swings - this would them obviate the need to have lots of different "USB-Serial" adapters - I already have a 3.3V and 5V and full range bipolar RS-232.   I can see that having a "Universal USB-Serial" adapter would be excellent.  Maybe just need to add some charge pumps?

David

Thanks, I have an add-on design ready for a piggy back PCB that adds isolated 'real' RS-232 +/- voltages but I haven't had the PCB made yet.

[ebclr]

This is what you need to have 232 level

https://pt.aliexpress.com/item/32890185940.html?spm=a2g0o.productlist.0.0.a44c4fe8cnRvnj&algo_pvid=d6d007ad-118e-487e-bec6-7436837074a2&algo_expid=d6d007ad-118e-487e-bec6-7436837074a2-1&btsid=0ab6fb8815865055753652989e7e87&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

Or this other option

https://pt.aliexpress.com/item/33024198471.html?spm=a2g0o.productlist.0.0.a44c4fe8cnRvnj&algo_pvid=d6d007ad-118e-487e-bec6-7436837074a2&algo_expid=d6d007ad-118e-487e-bec6-7436837074a2-10&btsid=0ab6fb8815865055753652989e7e87&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

[Gandalf_Sr]

I realize that there are various converters around, mostly based off the MAX232 IC, that convert 0-5V ogic to +/- 6V 'real' RS232.

I will post the schematic here but my adapter design (not yet built) includes an isolated 5VPSU module and digital isolators for the TX/RX lines.  Isolation was a feature I wanted and thought others would need too.

[coromonadalix]

Check the CY7C65213A  pdf, you can use the gpio4 to get a sleep mode with a max3245

https://www.cypress.com/file/139881/download

https://www.maximintegrated.com/en/products/interface/transceivers/MAX3245.html

[Gandalf_Sr]

Here's the design for the isolated, 'real' (+/- voltages), RS232 Extender.  It fits onto the side connector of my RS232 design above and then has a MAX3227 which I set up and tested on a breadboard.  It is a good choice as it automatically 'sleeps' while there's no traffic and 'wakes up' when RX/TX traffic appears.

It can be built with no isolation i.e. no isolated power supply and no digital converters (approx $5 saving on the BOM).

There's also a couple of pictures, first is the top view of the PCB in Diptrace, second is a 3D rendering from Diptrace.

There's a typo on the schematic, it should say this... "for non-isolated version, omit U1 & PS1 and fit R1, R4, R6, R7" (several ResDefs were wrong).

Let me know if you have suggestions for changes.

[coromonadalix]

Seems nice to me, but since i love tx rx traffic led to see if its communicating,   i would try to add cheap standard 3 mm leds

[Gandalf_Sr]

Seems nice to me, but since i love tx rx traffic led to see if its communicating,   i would try to add cheap standard 3 mm leds

If this were connected to my RS232 PCB (or most others e.g. Sparkfun one), you'd see the RX/TX lights there? I see LEDs on this extension PCB as unnecessary?