QC2.0/3.0 is the fast charging protocol for Qualcomm's mobile phone in recent years. Thanks to the market share of chips in the mobile phone field, QC3.0 fast charging has been widely used in mainstream models such as Xiaomi and ZTE. Here we will discuss with you the QC2.0/3.0 fast charge protocol decoding.
First, the introductionQC2.0/3.0 is a mobile phone fast charging protocol developed by Qualcomm in the past two years. Compared with the fast charging protocol of MediaTek and OPPO, Qualcomm QC fast charging technology has the highest market share in the smart phone field. QC2.0 is now becoming popular, and the ClassA standard for smartphones supports 5V, 9V and 12V input voltages. QC3.0 supports the gradient adjustment voltage of 200mv stepping on the basis of QC2.0. Currently, it has been supported free of charge in the ZDS4000 full range of oscilloscopes. Users can go to Guangzhou Zhiyuan Electronic Network to download the latest firmware free upgrade.
Second, the agreement description1. Protocol process
Figure 1 Protocol Process
2, voltage status
The QC fast charge protocol uses the D+ and D- pins of the USB interface to describe different states by changing the tristate voltage. The three states are 3.3V, 0.6V, and GND. The voltage status table is shown in Figure 2:
Figure 2 voltage status
Third, decoding examplesSince the QC fast charging protocol needs to distinguish between 0.6V and GND, the vertical position of the channel needs to be set to the appropriate position during decoding. The recommended one is 1V/div or 500mv/div. At the same time, since the waveform of the protocol generally lasts for a long time, it is recommended to use the ROLL mode to grab a waveform long enough to perform decoding analysis under STOP.
Suggested decoding steps:
1) Set the vertical scale and offset of each channel to fill the screen area as much as possible;
2) Adjust the horizontal gear position into the ROLL mode and grab the signal waveform for a certain length of time;
Figure 3 Long-term decoding results
Figure 4 Stepping value decoding
Figure 5 decoding of the reset signal
For the smart phone fast charging protocol, the ZDS4000 series oscilloscope can directly decode USB-PD and QC2.0/3.0.
(Source: ZLG Zhiyuan Electronics)
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