SX-ULPAN Frequently Asked Questions

Basic SX-ULPAN Specification Questions

What is the difference between the so-called “Ultra-Low Power Wi-Fi” and traditional Wi-Fi?

Answer: The ultra-low power Wi-Fi allows the use of a much smaller and lower power host CPU or even no host CPU, creating an overall smaller power draw for the system. So, ultra-low power Wi-Fi refers to the whole system power, and not just the Wi-Fi.

What makes QCA400x / SX-ULPAN different from "traditional" Wi-Fi is driver, supplicant and protocol (TCP/IP) offload. Traditional Wi-Fi requires Linux-class OS and several megabytes of memory on host system to run driver/supplicant. In the case of QCA400x/SX-ULPAN, minimum memory requirement is as low as 128KByte for code and 16KByte for data. Thus, it can reduce power requirement as whole system.


What is typical power consumption of the SX-ULPAN?


2.4 GHz





5 GHz





Uplink (IEEE PS)

2.2mA at 2.4GHz/DTIM=1

2.2mA at 2.4GHz/DTIM=1











Do I need an external CPU with the SX-ULPAN?

Answer: An external CPU or MCU is needed for the SX-ULPAN hardware with the driver version 3.0.2. However, our next version of the hardware will use v3.2 driver which will support host-less mode which will allow the Wi-Fi module to function as a complete autonomous system, without the need for an external CPU.



What CPU do you recommend to be used with SX-ULPAN?

Answer: Silex recommends using Freescale Kinetis family of MCU's. Our reference EVK uses a K21. However the SX-ULPAN is not limited to just the Kinetis family the SPI driver can ported to alternate MCU's and OS's.


What is difference between "SPI mode" and "UART mode" of SX-ULPAN?

Answer: "SPI mode" uses SPI interface and QCA wmiconfig. "UART mode" uses a UART interface and modem AT commands. 

Note: "UART mode" firmware has not been released so it is not currently supported.



Can I use SX-ULPAN via SDIO or USB?

Answer: These interfaces are not supported on the SX-ULPAN.



What is typical throughput of the SX-ULPAN?

Answer: Due to SPI limitations throughput is up to 10Mbps.

Note: QCA400x/SX-ULPAN SPI clock is up to 48MHz. It is limited to 30MHz with SX-ULPAN-EVK due to KinetisK21 SPI controller. With 30MHz SPI clock and 120MHz ARM Cortex-M4 core, actual throughput will be about 10Mbps.



What is maximum distance supported by SX-ULPAN?

Answer:  The Wi-Fi performance is comparable to the 6K3 radio, although it does not support the HT40 link rates.



Do you have Wi-Fi Certification Logo for SX-ULPAN?

Answer: The SX-ULPAN does not have Wi-Fi certification. Wi-Fi Certification is given to PRODUCT, and not to a COMPONENT. It is still POSSBLE that the end user product can be certified for Wi-Fi certification logo, and can be a time consuming task.



Does SX-ULPAN support Wi-Fi Direct?

Answer: SX-ULPAN supports Wi-Fi Direct only in client mode. Since we have not done Wi-Fi Direct certification, we do not openly advertise or support its functionality.

Does SX-ULPAN support Access Point mode?

Answer: It supports SoftAP mode with a maximum of 4 connections.


Does SX-ULPAN support Concurrent mode?

Answer: It does not support concurrent mode.



Does SX-ULPAN support WPS (Wi-Fi Protected Setup)?

Answer: SX-ULPAN supports WPS enrollee (station), no external registrar, PBC (Push Button Control) or PIN method (device PIN only).

Does SX-ULPAN support WoW (Wake on Wireless)?

Answer: It does not support Wake on Wireless function.


Does SX-ULPAN support MESH?

Answer: We do not support MESH on the SX-ULPAN



What is GreenTX?

Answer: GreenTX is Qualcomm-Atheros proprietary function and only works when connected to a GreenTX-capable Access Point. This feature allows the device to save power when communicating with a nearby station or access point when high output power is not required to sustain reliable communications. In such cases, the transmitter will reduce the transmit power to obtain current saving, while maintaining its high uplink throughput.

The QCA400x supports this function, but we at Silex have not tested the SX-ULPAN for this feature. Cannot comment how much power saving is expected with this function.



What is Low Power Listen Mode?

Answer: To minimize active current consumption, the QCA4004 firmware will set the receiver in a low power listen mode, thus saving active power in between frames, when the transceiver is awaiting frames, as well as during active reception. It can be enabled in most conditions with minimal performance impact, between 1 and 2 dB. If harsh channel conditions require it, firmware will automatically revert to full power mode.

If the SX-ULPAN interface method is determined absolutely by the firmware loaded, then does the customer have to support the HostMode bootstrap pins?

Answer: The firmware is specific to an interface type but the customer still need to configure the correct HostMode bootstrap to make sure the hardware is configured correctly.

SX-ULPAN Driver Questions


Do I need driver for SX-ULPAN, or is SX-ULPAN driver-less?

Answer: You require a SPI driver on the host.



Do I need firmware for SX-ULPAN?

Answer: Yes. The SX-ULPAN has the firmware in the “on-module” flash memory.



Do I need OS (RTOS) for SX-ULPAN?

Answer: No. QCA400x driver 3.0.2 supports non-OS mode. Though QCA400x driver has build option for non-RTOS system, but we RECOMMEND RTOS, as we have not evaluated the non-RTOS option.



Can I use SX-ULPAN on Linux or Android?

Answer: It is theoretically possible to run SX-ULPAN driver on those OS; however it must run as independent application. OS-provided protocol stack (including TCP/IP) cannot be used. Thus, it significantly reduces usefulness. There would be little practical value to use SX-ULPAN on Linux/Android - it is slow, limited functionality, no API compatibility.



Can I use SX-ULPAN on Windows or Windows CE?

Answer: Linux/Android/Windows question is trick question. It is theoretically possible to run SX-ULPAN driver on those OS; however it must run as independent application. OS-provided protocol stack (including TCP/IP) cannot be used. Thus, it significantly reduces usefulness.

How much is typical memory consumption for SX-ULPAN driver?

Answer: 60KByte for SPI stack.



How much is CPU usage for SX-ULPAN driver?

Answer: No Data. We have not measured the CPU usage.


Let me know what CPU and RTOS have you implemented for SX-ULPAN?

Answer: Freescale MQX (v4.0.2) with Kinetis K21.



Is it easy to port SX-ULPAN driver?

Answer: It is not trivial. It depends on a number of factors including:

-          If we previously have ported to that CPU/RTOS or not

-          If not, similarity between existing system and new system

-          Memory capacity and BSP support is another factor

If target system already has running RTOS BSP with working SPI driver, it is definitely easier than porting to a new platform.



Can I get SX-ULPAN driver source code?

Answer: It is downloadable from the Qualcomm's developer site.



Can I get SX-ULPAN firmware source code?

Answer: No, this is only available to a small group of QCA AADC's (Authorized Atheros Design Center) like Silex.



How can I upgrade driver or firmware of SX-ULPAN?

Answer: The driver would need to be updated in the host MCU's code.

SX-ULPAN firmware can be updated using SPI communication channel (called BMI loader). On SX-ULPAN EVK, we provide firmware update method over UART, using so-called Host.exe Windows command line program provided from QCA. Alternatively you can design your host system to "override" on-module SPI flash memory for firmware update. SX-ULPAN module has pins for SPI flash override; however these pins are NOT WIRED on SX-ULPAN EVK.



 Is the SX-ULPAN-2401 SPI command set identical to the factory QualComm SPI commands?   or are there Silex enhancements to this cmd set also.

Answer: The command set is the same as the QCA. We have updated the radio firmware but with the current verison there is no command update.

Will there be a path for to upgrade the module firmware after the modules are fielded?   or are the customers stuck with the version they ship with?

Answer: The current version of both the  SPI (SX-ULPAN-2401) and UART (SX-ULPAN-2402) have no in-field update capability for the radio firmware. We are releasing a new version of the device called the SX-ULPAN-2404 which is a UART version that will support OTA. This has a compatible UART command set with the ULPGN.

SX-ULPAN Protocol Stack Questions


Can I use SX-ULPAN with TCP stack outside of the chip?

Answer: Yes you can.



Does SX-ULPAN support IPv6?

Answer: Yes, SX-ULPAN supports IPv6.


Does SX-ULPAN support 6LowPAN?

Answer: 6LowPAN is a variant of IPv6 protocol, mainly designed for 802.15.4 radio (ZigBee), defined as RFC6282. The design principle of 6LowPAN is to reduce header size of IPv6 protocol in order to fit rather short 128-byte 802.15.4 frame size.

SX-ULPAN on-chip IPv6 stack does not support 6LowPAN. It is still possible to implement 6LowPAN by disabling IP offload, however because Wi-Fi can handle full-size Ethernet frame, there is little practical value to support 6LowPAN on Wi-Fi.


Does SX-ULPAN support Smart Energy Profile V2?

Answer: Smart Energy Profile is proposed standard power-grid control protocol for ZigBee. There are two versions are released; SEPv1 is specific to ZigBee, SEPv2 is IPv6 based protocol (IPv6 + TLS + HTTP + XML). So theoretically it is possible to run SEPv2 on any network architecture - including SX-ULPAN, however we silex do not provide support or sample implementation for SEPv2 on SX-ULPAN.


Does SX-ULPAN support Echonet Lite?

Answer: Echonet is a Japanese appliance connectivity protocol. Echonet lite aimed to be the standard power-grid control protocol in Japan.

Again Echonet lite is IP-based protocol (unlike SEPv2, it does not rely on HTTP/TLS. It use proprietary UDP format on port 3610). It can be implemented on SX-ULPAN, but again we silex do not provide any support or sample implementation for Echonet lite on SX-ULPAN.


Does SX-ULPAN support IPsec?

Answer: IPsec is not supported.



Does SX-ULPAN support SSL/TLS?

Answer: SX-ULPAN supports SSL/TLS, and works in server or client both. It supports only one session at a time. API and configuration is not well-documented, and not easy to use.


Let me know list of RFC supported by SX-ULPAN?

Answer: Listing RFC numbers can be tricky and deceiving. Listing RFC numbers does not guarantee the implementation is 100% compliant. RFC is not an implementation specification unlike IEEE standard, and there is no practical certification system to certify its implementation. Please contact if you need more information regarding RFC and SX-ULPAN.



What is AllJoyn?

Answer: AllJoyn is one of proposed standard protocol for IoT, provided from AllSeen Alliance, which is mainly driven by Qualcomm. AllJoyn code for QCA4004 is provided by Qualcomm; however we have not tested this feature and do not claim support.







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