RLink ERNI connector support for STM8

Why doesn't my RLink include an ERNI 4-pin connector or flat cable with the ERNI connector?

RLink uses a connection adapter for STM8 that has historically included an ERNI 4-pin connector for the STM8 SWIM programming / debugging interface.

Due to supply problems with the ERNI connectors, RLinks produced after 1 October 2022 do not included the flat cable for the ERNI connector.

For connection for STM8 SWIM protocol, use either the 10-pin connector on the provided STM8 adapter, or use the RLink 24-pin connector (without the adapter). The pin signals are provided in the tables below.

What do I do if I use the ERNI 4-pin connector on my application boards?

You can make pin-to-pin connections. The following information is provided to help you make the correct connections.

RLINK SWIM connectors


4 pts

10 pts

24 pts
20 pts
VCC** 1 7 1 1, 2
SWIMDATA*** 2 2 6, 12, 15* 3, 7, 13*
GND 3 1, 3, 5, 10 3, 4, 10, 17, 19, 21, 22 4, 6, 8, 10, 12, 14, 16, 18, 20
RST 4 6 9 17

* All three pins must be connected.

** the target board uses VCC to instruct the RLink on the signals voltage reference.

*** An additional 2K2 pullup resistor on SWIMDATA to VCC is required if there is no pullup on the target board.The resulting pullup, taking the RLink internal pullups in consideration,
should be around 1K and never less than 500 Ohms.

Here are links to the PDF schematics for the adapters supporting STM8 SWIM:

Note that you could also: 

  • Use the ERNI flat cable reference 839086
  • Or create your own cable using the ERNI connector reference 384528

For information about the ERNI connector above, and the purchasing and lead times, contact ERNI at http://www.erni.com.