[Enjoy the ride] Series 3: TekScope, the master of Tektronix oscilloscopes, helps you decode D-PHY/C-PHY

Tektronix provides TekScope PC client for waveform acquisition and analysis of oscilloscopes. Usually, waveform decoding and analysis are performed on the oscilloscope, which requires data copying and processing back and forth, and occupies oscilloscope resources. Using TekScope PC client, you can remotely acquire waveforms on multiple oscilloscopes, and perform MIPI D-PHY/C-PHY decoding, search and analysis on your own computer. This article mainly introduces the use and steps of TekScope PC for MIPI D-PHY/C-PHY decoding.

1. Waveform acquisition

After opening the TekScope software, you can add the oscilloscope that needs to collect waveforms by clicking "Add New Scope" below the oscilloscope. In the pop-up dialog box, you can see that the oscilloscope can be connected via the network or USB. You only need to enter the IP address of the corresponding oscilloscope and click "Connect"; when you have multiple oscilloscopes, you can also name the oscilloscope in "Label".

2. MIPI C-PHY decoding settings

After the oscilloscope acquires the waveform, click "Add New Bus" at the bottom of the software interface to add a new decoding bus.

Figure 3a. Adding the bus standard to be decoded

Figure 3b. Add bus decoding interface

In the pop-up bus selection interface, select CPHY in the drop-down list of "Bus Type" and select CSI or DSI decoding in "Sub Type". As shown in Figure 3b, the original C-PHY single-ended signals VA, VB and VC can be decoded. At this time, you need to select "Single Ended" in "Signal Type". At this time, you can see that the signal source "Source" is reflected as three signals A, B, and C in the interface. Next, you need to determine the decision level of the signal to be decoded.

There are two types of threshold levels in CPHY decoding. The "Threshold" specifies the intermediate decision level of the high-speed HS signal, which is usually zero. It can also be modified in more detail according to the specific situation of the signal, but it must be an intermediate level. The "LP Threshold" input is the distinction level between the LP signal and the HS signal. When setting this level, please note that the actual HS signal is not allowed to exceed it, but it cannot exceed the maximum 1.2V level specified by the LP signal.

In the same interface, you need to enter the rate of the high-speed HS signal in the "Bit Rate" input box, and then select "On" in Display, and TekScope can perform correct decoding. In addition, you can also customize the display of the bus and decoding according to your own preferences in "Display Format" and "Decode Format".

Figure 4

3. Open and locate the waveform decoding table

In order to facilitate the browsing of decoded signals, TekScope PC can display and locate the decoded results in a table format. The usage is divided into three steps:

1) Select "Results Table" from the first-level menu in the upper right corner of the software interface;

2) Select "Bus Decode" in the Type of Results Table;

3) Click "Add" to add the decoding result table

Figure 5. Adding a decoding table in three steps

The decoding table lists all the decoding fields and results, and by clicking on any decoding result, the software will automatically jump to the corresponding waveform, which is very convenient for positioning and debugging the decoding waveform, and the elements such as RGB in the pixel will be marked with the same color. The decoding table also supports the output of csv format, just right-click the decoding table and select "Save Table".

Figure 6. Automatic positioning of the decoding table and pixel color identification

4.Use the decoding search function of TekScope PC

TekScope PC can also search for marks based on bus decoding. For CPHY bus decoding, various data types and detailed data can be searched, as shown in the figure below. All types of data such as SOT, EOT, Data, Packets, etc. can be searched specifically. Just click the "Search" button on the first-level menu in the upper right corner of the software, then select the previously defined CPHY bus in "Source", and finally select the corresponding search condition in the "Mark On" drop-down list to define it.

The following example searches for pixels with Red data of "0x06" in RGB444 encoding under the Long Packet type:

Figure 9. Example of CPHY pixel-level search and positioning function

By adding "Search" through similar operations in the third point "Results Table", the search results defined previously can be displayed in a list. Similarly, the result list has corresponding timestamps and can be clicked to automatically jump, which is very convenient.

5. MIPI D-PHY bus decoding settings

The settings for MIPI D-PHY bus decoding and search are similar to those for MIPI C-PHY. The only difference is that in the Add New Bus interface, the following steps are used to implement it:

1) Select DPHY under "Bus Type";

2) "Protocols" specifies whether it is CSI or DSI standard;

3) Specify the Threshold of Clock and Data Threshold of Data. Note that this is the decision threshold level of the HS signal.

4) Specify the "LP Threshold" level to distinguish between LP and HS signals. The level here should be higher than the highest level of the HS signal but not higher than the 1.2V standard level of the LP signal.

5) Select a custom decoding format

Figure 10. MIPI D-PHY signal decoding setting interface

Likewise, the decoding and search tables mentioned above may also be used to perform waveform decoding search and positioning analysis.

In summary, TekScope PC supports remote acquisition, bus decoding, search and positioning of MIPI waveforms on personal computers, which makes it convenient for engineers to remotely decode and analyze MIPI on oscilloscopes, save oscilloscope resources, facilitate data collation and remote collaboration, and is fast and comprehensive in functions. It also supports different oscilloscope platforms such as Tektronix DPO70k and MSO6B, which is of great help to engineers who have MIPI bus decoding and analysis requirements.