QC2.0 / 3.0 is Qualcomm in recent years, the main push of the mobile phone fast charging protocol, thanks to the chip in the field of mobile phone market share, QC3.0 fast charging has been widely used in millet, ZTE and other mainstream models. This article and we jointly discuss QC2.0 / 3.0 fast charge protocol decoding.
一、Introduction
QC2.0 / 3.0 is Qualcomm in the past two years to develop mobile phone fast charge agreement, compared to MediaTek and OPPO fast charge agreement, Qualcomm QC fast charging technology in the field of smart phones the highest share. QC2.0 is now becoming popular, for the smart phone custom ClassA standard support 5V, 9V and 12V input voltage. QC3.0 on the basis of QC2.0, 200mv step to support the gradient adjustment voltage. ZDS4000 has a full range of oscilloscopes in the free support, the user can go to Zhiyuan electronic network official download the latest firmware free upgrade.
二、the agreement description
1、the agreement process
Figure 1 protocol flow
2、the voltage state
The QC fast charge protocol uses the D + and D- pins of the USB interface to describe different states by tri-state voltage changes. The three states are 3.3V, 0.6V and GND, respectively. The voltage status table is shown in Figure 2:
Figure 2 Voltage state
三、decoding examples
Since the QC fast charge protocol needs to distinguish between 0.6V and GND, the vertical stall of the channel needs to be set to the appropriate location at the time of decoding, and Harvatek recommends 1V / div or 500mv / div. At the same time, because the waveform of the protocol generally lasts longer, it is recommended to use ROLL mode to capture a long enough waveform, and then under the STOP decoding analysis.
Suggested decoding steps:
(1) set the vertical position and offset of each channel, as far as possible to fill the screen area;
(2) adjust the level of gear into the ROLL mode, grab a certain length of time the signal waveform;
Figure 3 long decoding results
Figure 4 Decoding of step value
Figure 5 Decode the reset signal
For the smart phone fast charging protocol, ZDS4000 series oscilloscope can directly decode USB-PD, QC2.0 / 3.0.
