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Rs485-ch340e

TG9541·rs485-ch340e

Rs485-ch340e PCB layout, top view — open source board by TG9541
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About the Rs485-ch340e PCB

Rs485-ch340e is an open source PCB design by TG9541, published on GitHub under the MIT license. It is a 2-layer board measuring 16.9 × 14.4 mm, with 14 components from 12 distinct parts.

Other key parts include the CH340E, SP3485CN and XC6206P332MR. By type, the board carries 3 ICs, 3 diodes, 3 capacitors, 2 connectors, 2 resistors and 1 switch.

It belongs with the usb & debug tools designs in this gallery.

From the project

A small CH340E based configurable RS485 or TTL 2/3-wire USB dongle

I needed a USB-RS485 dongle with reliable automatic direction control but it was impossible to find anything that's both reliable and cheap (not to speak of small). The "budget" cmmercial USB-RS485 dongles "try" to implement direction controll with the host's Tx signal. The timing of such a solution is tricky (and potentially unreliable). A "popular" work-around is using a questionable "dominant-recessive" approach to RX-TX switching with a "CAN network style" recessive default state. Such a hack is certainly not RS485 compliant and may randomly fail if multiple nodes are connected, the bus…

Rs485-ch340e, from the project README
From the project README

Main components on the Rs485-ch340e

CH340ESP3485CNXC6206P332MR

Rs485-ch340e bill of materials (BOM)

14 components, 12 distinct parts — part numbers from the project's BOM.

QtyPartRefs
1
CH340E
U1
1
SP3485CN
U2
1
XC6206P332MR
U3
1
USB_A
J1
1
Conn_01x04_Male
J2
1
SW_SPDT
SW1
1
DIODE
D1
1
LED red
D2
1
LED green
D3
2
1uF
C1, C2
1
100nF
C4
2
4k7
R1, R2

Rs485-ch340e design files

The KiCad project lives in the TG9541/rs485-ch340e repository on GitHub; these links point at the commit this page was built from.

Rs485-ch340e: common questions

How big is the Rs485-ch340e PCB?

The Rs485-ch340e measures 16.9 × 14.4 mm, has 2 copper layers and is 0.999998 mm thick.

How many components are on the Rs485-ch340e?

14 components, from 12 distinct parts, with part numbers taken from the project's own BOM. The full bill of materials is listed on this page.

Where can I download the Rs485-ch340e design files?

From the TG9541/rs485-ch340e repository on GitHub, which has the KiCad layout and the BOM; the links under Design files point to each one.

Can I use the Rs485-ch340e design in my own project?

Yes, under the terms of its MIT license, which TG9541 chose for the repository.

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