The P1,S1 & S2 Chipsets are custom Asics used by DJI in their Ocusync based drones that are the basis for their Ocusync RF Wireless Link. These chipsets are similar to early Leadcore SOC’s and are believed to be direct “descendants”.
The P1,S1 and S2 chipsets have only ever been found in DJI products or products licensed by DJI such as the CaddX Vista and a strongly believed to be inhouse custom Asics.
They can be found in any Ocusync based DJI product from their Consumer and Enterprise drones to DJI Transmission and are deemed as one of their “Crown Jewels”
In early 2024 the P1 chipset has been found in drones sold under the banding of Cogito Tech Company such as the Specta Air, Specta Mini as well as the Raptor by Anzu Robotics. These drones are technically identical to DJI models including PCB boards having the same design, part numbers and containing the P1. This is evidence these are “white labeled” DJI Drones.
History
DJI originally used a Leadcore chipset specifically the LC1860 on their older Ocusync based drone models including the Ocusync Air FPV system. Ocusync was was first seen on the Mavic Pro as is a replacement for the Lightbrige system that DJI had previously used. It’s big difference was it’s an SDR based of off the shelf hardware rather than hardware based radio. After Ocusync introduction It was used on a Leadcore chipset right up to the Mavic 2 Pro. Just to explain about Leadcore , they are a Chinese foundry-less chip designer that makes SOC for tablets, phones and smart devices. The Leadcore SOC is all in one with both the system processors and RF Modems on a single chip. They are not widely used and also not particularly good ones either as what DJI was using was made in 2017 and not exactly cutting edge, it’s not up there with snapdragon, Apple A series ect. The specific chipset DJI was using is the LC1860. The P1 SOC appeared for the first time in the Mavic 2 Pro B remote and replaced the Leadcore chip, the craft continued to ship with the Leadcore as i understand it. Overall nothing from Ocusync performance point of view changed other than it is DJI first use of the P1 in its Ocusync 2 system, It’s basically like for like compatible on the Ocusync front. The P1 then next appeared in the new FPV system and then subsequently in all their consumer drones right up to the Mavic 3 and we almost defiantly in the Mini 3 to.
The P1 appears to be a customized version of that initial Leadcore SOC. All of the extras “bits” that’s was not needed for DJI application was removed and it’s tweaks to make it more specific. Again nothing ground breaking just a custom Asic solution rather than the off the shelf option. Inside the P1 (Pigeon) is pretty much a copy of Leadcore’s architecture. It’s got two big Cortex-A7 cores, some small ones, the dsp etc. and a few other bits. (and a bucket load of on die RAM on S1). They are basically using the same CPU core + DSP setup as the Leadcore chipset and it’s likely running custom software for their LTE based OcuSync and this is what’s making the difference. The P1 first big core runs linux, 1 runs the rtos in combination with the dsp-s.
The small cores are used for trust zone os and other things. It also has very limited capabilities for video as it’s mostly an encoder, decoder, MIPI input and HDMI output, a multi-phy LTE. This is why it offloads camera control ect to the AP1302 DSP on the 120fps models as there is nothing onboard to do it. There is also a S1 (Sparrow) variant that only does RF side of things and uses Cortex-M instead of Cortex-A for the application processor and communication processor and is used in the newer remotes like RC231 etc where video is offloaded to another SOC such as the Eagle H3 chipset. While it’s clear the P1 is extremely capable based on its actual performance we have seen with it in the various Ocusync based systems it remains the case nothing in the P1 is latest tech or even that secret or impressive. Its Arm cores, SDR, RAM, MIPI, HDMI and USB interface. There are far more powerful and more capable chipsets out there today that could be used for instance to do the same thing. There are some newer ones designed for the 5G market that will be easily be more powerful that this 2017 based chipset DJI is using.
P1 & S1 Usage
The Pigeon 1 aka P1
The P1 supported carriers up to 40Mhz, dual antennas and onboard video decoding and has been used in most DJI drones with Ocusync 2 and Ocusync 3. This includes Enterprise models and ground based DJI wireless products such as DJI Transmission.
Ocusync 2 based models uses the onboard Arm cores of the P1 for video processing such as in the DJI Mavic 2 and the DJI Digital FPV system with the Ceva DSP as the RF modem.
Ocusync 3 based product uses the P1 along side a second media processor such as the E3T and offloads video processing to that leaving the P1 largely as a modem.
The Sparrow 1 aka S1
Due to its limited bandwidth up-to 20Mhz and processing the S1 is generally used in lower end DJI products like the Mini series or DJI remote controllers where the additional bandwidth and Arm cores is not required as video processing is offloaded to an secondary SOC. In this case the S1 acts largely as a modem.
DJI O3 & The P1
In both the Avata and O3 Air Unit DJI use the P1 along side the E3T. In this use case the bigger arm cores of the P1 are largely redundant. The ideal setup for this use case would actually have been an S1 with the E3T however this would have limited its bandwidth to 20Mhz (25Mbps) and as such DJI had to still use the P1.
More info on the O3 Airunit can be found here.
Ocusync 4 (O4) & The Sprarrow 2 aka S2
In 2023 DJI released drones with Ocusync 4 and a new variant of the chipset called the Sparrow 2 (S2). This is an upgraded S1 featuring increased bandwidth up to and beyond 80Mhz and more antenna lanes. This solved the issues DJI faced with O3 having to use the P1.
This is usually coupled to a second chipset for video processing such as the Eagle3T or H6 like in the DJI Mini 4, Avata and O3 Air Unit however has improved capabilities over both the S1 and P1.
The S2 is found in models Mini 4 Pro, Avata 2. DJI RC 2 and RCN2.
Technically S2 chipsets offer compatibility with the previous S1 and P1 however not all features will work such as the increased 60 and 80Mhz bandwidth modes.
CaddX Walksnail Avatar HD Artosyn AR9201 – Its Not DJI
There has been lots of questions around the Avatar HD system and if it was using the same chipset as DJI.
The main chipset used in Avatar HD is Artosyn AR9201/AR8211. This is a similar chipset to the DJI P1 being an CPU and RF base band all in one with Arm cores and Ceva LTE ISP. This chip is not the same as DJI’s though and is believes to be developed separately from the DJI P1 and S1. Both Chipset share a lineage to chipsets from Leadcore such as the LC1860C as used by DJI and others in the past all based of china inhouse designed SOC for use smartphone and tablets based on LTE Ceva ISP’s.
It is also worth noting that DJI has worked with Artosyn in the past on their RF systems and we have suspicions after the fall of Leadcore DJI may have worked with Artosyn to help develop their own SOC. DJI has worked with Artosyn in the early days of Lightbridge and Ocusync development and may have even contributed to the P1 and S1. While there is some possible heritage between the chipsets they are not compatible with each others systems in any way.
Both Chipset share a lineage to chipsets from Leadcore such as the LC1860C
#DJI FPV #DJI O3 #DJI P1
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