This article serves as an introduction.
Online programming, integrating programming and testing, has garnered increasing attention. To enhance programming efficiency, programming fixtures or jigs are often created, and the connection between the fixture, jig, and programmer typically requires longer wiring. The longer the wiring, the faster the signal attenuation, which increases the programming failure rate. This article will introduce how to improve issues such as programming failures or instability caused by excessively long wiring.
Figure 1 Online Programming Fixture
1. Add Shielding Layer to Prevent Electromagnetic and Static Interference
The programmer, as a tool closely communicating with the chip, is sensitive to electromagnetic interference. The programming environment is generally a factory workshop with high-power equipment, leading to significant electromagnetic interference. To reduce this interference, we can add a shielding net to the programming line or choose cables with shielding capabilities, such as shielded cables or network cables. Additionally, it is best to wear anti-static gloves during operation to prevent static interference.
2. Choose Wires with Strong Conductivity
The integrity of signal transmission is related to the material, length, and thickness of the wire. Choosing thicker wires with better conductivity can reduce internal resistance and lower signal loss, such as pure copper wires, gold-plated wires, or silver-plated wires.
Figure 2 Metal Resistivity
3. Reduce Communication Frequency
Communication frequency is a crucial parameter for information transmission. The higher the frequency, the faster the transmission speed, but signal attenuation increases with frequency and rapidly weakens with increased transmission distance. Therefore, when wiring is longer, it is advisable to reduce the communication frequency to enhance stability.
4. Connect Pull-up or Pull-down Resistors on Key Signal Lines
Some chip programming interfaces have weak driving capabilities and require appropriate pull-up or pull-down resistors to enhance driving ability. For example, IIC and SWIM interfaces need strong pull-up resistors on data lines, while automotive key chips like PCF79xx and NCF29xx require pull-down resistors on clock lines, etc.
5. Choose Programmers with Strong Driving Capability
The driving capability of the programmer’s pins directly affects the wiring length. Some commercially available online programmers directly expose the IO ports of the internal control chip or FPGA pins as input and output for programming signals, which have weak driving capabilities. When the user’s wiring is relatively long (generally greater than 30cm), signal distortion occurs, leading to programming instability. When selecting a programmer, it is essential to choose a professional online programmer, such as the P800isp programmer from Zhiyuan Electronics, which enhances driving capability through multi-channel signal processing, solving a series of problems caused by long wiring.
Figure 3 Comparison of Waveforms between P800isp and Some Programmers
Zhiyuan Electronics Introduction
Guangzhou Zhiyuan Electronics Co., Ltd. was established in 2001 and is a nationally recognized high-tech enterprise and the Guangdong Provincial Engineering Technology Research and Development Center for high-end industrial control measurement instruments.
Vision:To become the leading enterprise in the industrial internet ecosystem
Design high value-added modules, boards, and high-end measuring instruments using the “chip + AWorks software platform”. Through wired and wireless interfaces, connect to the ZWS IoT cloud, achieving big data processing and forming an industrial internet ecosystem.
Mission:To advance the process of China’s industrial internet with leading technology
Values:Professionalism and Focus Achieve Dreams