APPLICATION NOTE
REDFIT IDC SKEDD Connector
A new connection for debug and firmware-upload
ANE004 BY DANIEL KÜBLER IN COOPERATION WITH GÜNTHER KLENNER FROM 
1 Connection of debugger and micro-controller
During development, the connection between the debugger and a micro-controller is important to upload firmware, validating codes or finding mistakes. Even during production of small and mid-size series this connection is used for uploading firmware after mounting. Commonly a box-header is mounted on the PCB to connect the debugger. But mostly this component is single used only and needs space, build height and money. Not only the cost of the part itself has to be considered, as there are purchasing- and production-processes generating costs as well. But an initial connection is necessary to bring the firmware to the micro-controller. For high volume production MCUs are programmed before mounting, but for small and midrange quantities it is not economic in terms of costs as well. Würth Elektronik now provides a solution perfect to use even for small series.
Figure 1: Würth Elektronik REDFIT IDC SKEDD Connector
2 Debugger connection without boxheader
Würth Elektroniks` new REDFIT IDC SKEDD connector is directly connected to the PCB by hand without the need of a counterpart. Means no extra costs for component, processing or purchasing. There´s even no space needed above the PCB, which benefits the housing designer. Nonetheless the connector provides secure connection without any additional tool. Thereby debugging of the firmware can be easily processed after production. Two differently sized plastic pegs protect the REDFIT IDC SKEDD against polarity reversal. This safety feature prevents damaging the debugger as well as the micro-controller. Another interesting feature: The plastic pegs are longer as the contacts. Therefore no shortcuts can occur by touching the board on wrong position or below mounting plate.
3 2-Wire Debugger
Most of the micro-controllers provide the possibility of a two wire debugging. For ARM MCUs it´s named Wire-Debug, for TI-MSP430 SpyBi-Wire but even other MCU showing this feature nowadays. Thereby only two pins of the MCU instead of five (JTAG) are used for debugging. Means three pins can be used for the application. A great benefit as mostly the micro-controller never have enough pins (by customer wish). Additionally the connector and PCB can be realized in a smaller form factor. Certainly two additional lines are needed for power supply, so it ends up with a 4-wire connection finally. The following graphics show the four lines in a schematic of TI-MSP430:
Figure 2: Debug-lines and power supply in TI-MSP430 schematic (Source: TI MSP430 – Hardware Tools User´s Guide Lit-No: SLAU278)
4 REDFIT IDC as 4-Pin Debug Plug
First tests performed with MPSP430G2553 show all advantages named above. The space needed for the connection could be integrated between the components:
Figure 3: Layout and required space on the PCB
Used pinning:
1 = Vcc
2 = Clock
3 = Data (Reset)
4 = GND
Figure 4: Pinning of REDFIT IDC SKEDD as debug-connector
Due to the used pinning the current carrying lines are maximum spread and enables a specific reset when shorting pin 3 and 4. The REDFIT IDC SKEDD connects properly without any wiggling. A flexible 4-wire flat wire leads securely to the debugger:
Figure 5: REDFIT IDC SKEDD during debugging
5 Conclusion
The new WE REDFIT IDC SKEDD connector fits perfectly for debug connections. Both in design stage and for small and midsize volume production. It´s a secure, performed by hand connection without any need of a counterpart.
IMPORTANT NOTICE
The Application Note is based on our knowledge and experience of typical requirements concerning these areas. It serves as general guidance and should not be construed as a commitment for the suitability for customer applications by Würth Elektronik eiSos GmbH & Co. KG. The information in the Application Note is subject to change without notice. This document and parts thereof must not be reproduced or copied without written permission, and contents thereof must not be imparted to a third party nor be used for any unauthorized purpose. Würth Elektronik eiSos GmbH & Co. KG and its subsidiaries and affiliates (WE) are not liable for application assistance of any kind. Customers may use WE’s assistance and product recommendations for their applications and design. The responsibility for the applicability and use of WE Products in a particular customer design is always solely within the authority of the customer. Due to this fact it is up to the customer to evaluate and investigate, where appropriate, and decide whether the device with the specific product characteristics described in the product specification is valid and suitable for the respective customer application or not. The technical specifications are stated in the current data sheet of the products. Therefore the customers shall use the data sheets and are cautioned to verify that data sheets are current. The current data sheets can be downloaded at www.we-online.com. Customers shall strictly observe any product-specific notes, cautions and warnings. WE reserves the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services. WE DOES NOT WARRANT OR REPRESENT THAT ANY LICENSE, EITHER EXPRESS OR IMPLIED, IS GRANTED UNDER ANY PATENT RIGHT, COPYRIGHT, MASK WORK RIGHT, OR OTHER INTELLECTUAL PROPERTY RIGHT RELATING TO ANY COMBINATION, MACHINE, OR PROCESS IN WHICH WE PRODUCTS OR SERVICES ARE USED. INFORMATION PUBLISHED BY WE REGARDING THIRD-PARTY PRODUCTS OR SERVICES DOES NOT CONSTITUTE A LICENSE FROM WE TO USE SUCH PRODUCTS OR SERVICES OR A WARRANTY OR ENDORSEMENT THEREOF. WE products are not authorized for use in safety-critical applications, or where a failure of the product is reasonably expected to cause severe personal injury or death. Moreover, WE products are neither designed nor intended for use in areas such as military, aerospace, aviation, nuclear control, submarine, transportation (automotive control, train control, ship control), transportation signal, disaster prevention, medical, public information network etc. Customers shall inform WE about the intent of such usage before design-in stage. In certain customer applications requiring a very high level of safety and in which the malfunction or failure of an electronic component could endanger human life or health, customers must ensure that they have all necessary expertise in the safety and regulatory ramifications of their applications. Customers acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any use of WE products in such safetycritical applications, notwithstanding any applications-related information or support that may be provided by WE. CUSTOMERS SHALL INDEMNIFY WE AGAINST ANY DAMAGES ARISING OUT OF THE USE OF WE PRODUCTS IN SUCH SAFETY-CRITICAL APPLICATIONS.
USEFUL LINKS
ANE004: REDFIT IDC SKEDD – Debugging & Firmware-Upload
Application Notes www.we-online.com/appnotes
REDEXPERT Design Plattform www.we-online.com/redexpert
Toolbox www.we-online.com/toolbox
Produkt Catalog www.we-online.com/products
CONTACT INFORMATION
Tel. +49 7942 945 - 0
Würth Elektronik eiSos GmbH & Co. KG
Max-Eyth-Str. 1 ⋅ 74638 Waldenburg ⋅ Germany