Sensor and Performance

The VAXEE Zygen NP-01S Wireless is equipped with the PixArt PAW3395. According to specifications, the 3395 is capable of up to 26,000 CPI, as well as a maximum tracking speed of 650 IPS, which equals 16.51 m/s. Out of the box, four pre-defined CPI steps are available: 400, 800, 1600, and 3200.

CPI Accuracy

"CPI" (short for counts per inch) describes the number of counts registered by the mouse if it is moved exactly an inch. There are several factors (firmware, mounting height of the sensor not meeting specifications, mouse feet thickness, mousing surface, among others) which may contribute to nominal CPI not matching actual CPI. It is impossible to always achieve a perfect match, but ideally, nominal and actual CPI should differ as little as possible. In this test, I'm determining whether this is the case or not. However, please keep in mind that said variance will still differ from unit to unit, so your mileage may vary.


I've restricted my testing to the four most common CPI steps, which are 400, 800, 1600, and 3200. As you can see, there is no deviation at all, which is a perfect result.

Motion Delay

"Motion delay" encompasses all kinds of sensor lag. Any further sources of input delay will not be recorded in this test. The main thing I'll be looking for in this test is sensor smoothing, which describes an averaging of motion data across several capture frames, in order to reduce jitter at higher CPI values, increasing motion delay along with it. The goal here is to have as little smoothing as possible. As there is no way to accurately measure motion delay absolutely without special equipment, it is done by comparison with a control subject that has been determined to have consistent and low motion delay. In this case, the control subject is a Logitech G403, whose PMW3366 sensor has no visible smoothing across the entire CPI range. Note that the G403 is moved first and thus receives a slight head start.

Compared to earlier firmware versions of the XE Wireless, the process of switching to different sensor run modes has been simplified considerably. Previously, in order to select competitive mode, a designated firmware had to be flashed to the mouse. On the most recent firmware, competitive mode has been integrated into the regular firmware, and high-speed mode has been done away with entirely. Standard mode has been retained and functions identically to before.

Wired testing


By virtue of being restricted to 3200 CPI, the NP-01S Wireless does not have smoothing across the entire CPI range. There are several run modes worthy of further scrutiny, however: Without MotionSync (first row, left), with MotionSync (first row, right), without MotionSync but with competitive mode (second row, left), and with MotionSync and competitive mode (second row, right). Competitive mode does not have any apparent effect on tracking, whereas MotionSync tightens SPI timing.



In order to determine motion delay, I'm looking at xSum plots generated without MotionSync (first row, left), with MotionSync (first row, right), without MotionSync but with competitive mode (second row, left), and with MotionSync and competitive mode (second row, right). The line further to the left denotes the sensor with less motion delay. Competitive mode has no measurable effect on motion delay, whereas MotionSync increases motion delay by roughly 0.5 ms. Hence, the most responsive setting is without MotionSync, regardless of whether competitive mode is enabled. Based on these plots, we can infer that in wired mode, the NP-01S Wireless defaults to corded gaming mode regardless of other settings.

Wireless testing


Upon switching to wireless, SPI timing jitter increases considerably. Upon enabling competitive mode, tracking resembles wired mode, and upon enabling MotionSync, SPI timing jitter is tightened, much like in wired mode.



Much like in wired mode, enabling MotionSync increases motion delay by roughly 0.5 ms. Without MotionSync, a motion delay differential of less than 0.5 ms can be measured, which may be lowered even further by enabling competitive mode. Hence, the most responsive setting is with MotionSync disabled and competitive mode enabled, which is what the NP-01S Wireless is set to by default.


A rather curious behavior previously encountered on several releases from Razer (DeathAdder V2 Pro, V3 Pro, Viper V2 Pro, Naga V2 Pro, among others) and a few other manufacturers, including VAXEE with the XE Wireless, is present on the NP-01S Wireless as well. At any point during the motion, though typically at the start, motion delay is increased by a single interval (i.e., 1 ms), which is maintained through the motion. This can happen in both wired and wireless mode and regardless of which setting is active at the time. I'm unable to reproduce this behavior consistently.

Speed-related Accuracy Variance (SRAV)

What people typically mean when they talk about "acceleration" is speed-related accuracy variance (or SRAV). It's not about the mouse having a set amount of inherent positive or negative acceleration, but about the cursor not traveling the same distance if the mouse is moved the same physical distance at different speeds. The easiest way to test this is by comparison with a control subject that is known to have very low SRAV, which in this case is the G403. As you can see from the plot, no displacement between the two cursor paths can be observed, which confirms that SRAV is very low.

Perfect Control Speed

Perfect Control Speed (or PCS for short) is the maximum speed up to which the mouse and its sensor can be moved without the sensor malfunctioning in any way. I've only managed to hit a measly 5 m/s, which is within the proclaimed PCS range and causes no observable sensor malfunction.

Polling Rate Stability

Considering the NP-01S Wireless is usable as a regular wired mouse as well, I'll be testing polling rate stability for both wired and wireless use.

Wired testing

Of the available polling rates (125, 500, and 1000 Hz), only 1000 Hz looks and performs fine, whereas the others display periodic off-period polls.

Wireless testing
For wired mice, polling rate stability merely concerns the wired connection between the mouse (SPI communication) and the USB. For wireless mice, another device that needs to be kept in sync between the first two is added to the mix: the wireless dongle/wireless receiver. I'm unable to measure all stages of the entire end-to-end signal chain individually, so testing polling-rate stability at the endpoint (the USB) has to suffice here.


First, I'm testing whether SPI, wireless, and USB communication are synchronized. Any of these being out of sync would be indicated by at least one 2 ms report, which would be the result of any desynchronization drift accumulated over time. I'm unable to detect any periodic off-period polls that would be indicative of a desynchronization drift.


Second, I'm testing the general polling-rate stability of the individual polling rates in wireless mode. Running the NP-01S Wireless at a lower polling rate can have the benefit of extending battery life. As can be seen, both 125 and 500 Hz exhibit periodic outliers, leaving 1000 Hz as the only fully stable polling rate.


Interestingly, when using competitive mode, the interval at which off-period polls occur changes compared to the default firmware version. 1000 Hz continues to be the only fully stable polling rate available nonetheless.

Paint Test

This test is used to indicate any potential issues with angle snapping (non-native straightening of linear motion) and jitter, along with any sensor lens rattle. As you can see, no issues with angle snapping can be observed. There is no jitter visible at any of the tested CPI steps. Lastly, there is no lens movement at 3200 CPI, which is the highest CPI step on the NP-01S Wireless.

Lift-off Distance

The NP-01S Wireless offers two pre-defined LOD levels. At the default "Low" setting, the sensor does not track at a height of 1 DVD (<1.2 mm). Using the "High" setting, the sensor does track at a height of 1 DVD, but not at a height of 2 DVDs (1.2<x<2.4 mm; x=LOD height). Keep in mind that LOD may vary slightly depending on the mousing surface (pad) it is being used on.

Click Latency

In most computer mice, debouncing is required to avoid double clicks, slam-clicks, or other unintended effects of switch bouncing. Debouncing typically adds a delay, which, along with any potential processing delay, shall be referred to as click latency. In order to measure click latency, the mouse has been interfaced with an NVIDIA LDAT (Latency Display Analysis Tool). Many thanks go to NVIDIA for providing an LDAT device. More specifically, the LDAT measures the time between the electrical activation of the left main button and the OS receiving the button-down message. Unless noted otherwise, the values presented in the graph refer to the lowest click latency possible on the mouse in question. If a comparison mouse is capable of both wired and wireless operation, only the result for wireless (2.4 GHz) operation will be listed.

In wired mode and using a debounce time of 2 ms, click latency has been measured to be 3.2 ms, with standard deviation being 0.31 ms. In wired mode and using a debounce time of 3 ms, click latency has been measured to be 4.2 ms, with standard deviation being 0.34 ms. In wired mode and using a debounce time of 4 ms, click latency has been measured to be 5.2 ms, with standard deviation being 0.37 ms.

In wireless mode and using a debounce time of 2 ms, click latency has been measured to be 3.3 ms, with standard deviation being 0.37 ms. In wireless mode and using a debounce time of 3 ms, click latency has been measured to be 4.3 ms, with standard deviation being 0.37 ms. In wireless mode and using a debounce time of 4 ms, click latency has been measured to be 5.3 ms, with standard deviation being 0.41 ms.

The values above apply both to the competitive and standard mode.

The main button switches were measured to be running at 2.06 V. I'm not aware of the voltage specifications of the used Huano switches, but do find this voltage rather low.