Kunshan Muchun Electric Co., LTD , https://www.muchunmanufacture.com
How to improve the instability of the programmer programming chip
Online burning, integrated burning and testing, has been paid more and more attention. In order to speed up the burning efficiency, the burning tooling or fixture is often produced, and the tooling, the fixture and the programmer need a relatively long wiring. The longer the wiring, the faster the signal attenuation, and the burning defect rate also increases. It will introduce how to improve a series of problems caused by long wiring and programming failure or instability.
Figure 1 online burning fixture
First, increase the shielding layer to prevent electromagnetic interference and static interference
The programmer acts as a tool for close communication with the chip and is sensitive to electromagnetic interference. The burning environment is generally factory floor, high-power equipment, making electromagnetic interference more serious. In order to reduce electromagnetic interference, we can add shielding net on the burning line, or select the shielding function line, such as shielded cable, network cable, etc. Wear electrostatic gloves during operation to prevent static electricity.
Second, choose a line with strong electrical conductivity
The integrity of the signal transmission is related to the material, length and thickness of the wire. You can choose a thicker, more conductive wire. A good material can reduce internal resistance and reduce signal loss, such as pure copper wire, gold-plated wire, silver plated. Line and so on.
Figure 2 metal resistivity
Third, reduce the communication frequency
Communication frequency is an important parameter of information transmission. The higher the frequency, the faster the transmission speed, but the attenuation of the signal will increase with the increase of frequency, and it will weaken rapidly with the increase of transmission distance. Therefore, when the wiring is long, it can be appropriate. Reduce the communication frequency to increase the stability of communication.
4. Connect pull-up or pull-down resistors on the critical signal lines.
Some chip programming interfaces have weak drive capability. It is necessary to add appropriate pull-up or pull-down resistors on the interface to enhance the drive capability. For example, IIC and SWIM interfaces need to be connected with strong pull-up resistors on the data line. Car key chip PCF79xx , NCF29xx, etc. need to connect the pull-down resistor on the clock line and so on.
Fifth, choose a programmer with strong driving ability
The driver capability of the programmer pin will directly affect the length of the wiring. Some online support programmers on the market directly lead to the IO port of the internal control chip or the pin of the FPGA as the input and output of the programming signal. Weak, when the user's wiring is long (generally greater than 30cm), signal distortion will occur, resulting in unstable programming. When programming the programmer, you need to choose a professional online programmer, such as the Zhiyuan P800isp programmer. Through multi-channel signal enhancement processing, the driver's driving ability is increased, and a series of problems of long wiring are solved.
Figure 3 P800isp compared with some programmer waveforms