Renesas offers software stacks for a variety of sub-gigahertz (GHz)/Wi-SUN wireless communication applications.
Software for Renesas' sub-GHz wireless communication solutions is compliant with the Wi-SUN ECHONET Lite Profile international wireless communication standard and has been certified by Wi-SUN.
The software undergoes interconnection testing by the standardization organization, the Wi-SUN Alliance, so you can carry out system design for a wireless network with peace of mind. Choose from among three packages according to the needs of your
The RF driver is a program that controls the RF transceiver and offers a PHY layer-level API (tables 1 & 2). It carries out 50 or 100 kbps GFSK-modulated wireless communications in the IEEE802.15.4g wireless frame format. It also provides functions such as carrier sensing, which detects surrounding wireless conditions to avoid collision with transmissions from other wireless stations.
This RF driver is not OS-dependent, and can be adapted to a variety of systems. However, a transmission control function for the user's application must be implemented in order to obtain technical standard conformity certification and construction design certification for wireless equipment under the Japan Radio Law. Transmission control stipulated by the ARIB STD-T108 standard for 920 MHz wireless equipment used in Japan is also implemented. For example for ARIB STD-T108, for a carrier sensing time of 128 microseconds and 20 mW output or less, the maximum total transmission time is 360 seconds per hour. This solution satisfies this condition by keeping track of accumulated transmission time and controlling transmission accordingly.
Table 1. RL78 Family sub-GHz RF driver
Table 2. RX600 Series sub-GHz RF driver
The MAC stack (figure 3, tables 3 & 4) offers the MAC functionality stipulated by the IEEE802.15.4-2011-and IEEE802.15.4e-2012 specifications. IEEE802.15.4e-2012 includes a variety of optional functions. This MAC stack supports the functions that are necessary for realizing the IP stack which will be mentioned later and the mesh network.
Functions supported by this MAC stack
- Wireless frame transmission and reception in non-beacon mode
- CCA and CSMA-CA
- Acknowledge frame transmission and reception, data re-transmission
- Network scan and beacon frame response
- Indirect transmission to sleeping device
- MAC security
Table 3. RL78 Family Wi-SUN MAC-R protocol stack
Table 4. RX600 Series Wi-SUN MAC-R protocol stack
Standardization of communications specifications, especially for smart meters, is proceeding in the industry (figure 4). Standardization applies to a variety of services being born from the deregulation of the electric power industry, and aims to make power usage more efficient.
In particular, for the communication path between smart meters and HEMS, called route B, major electric power companies have adopted the ECHONET Lite specifications for the application layer and sub-GHz wireless communications or power line communication (G3-PLC) for its communication layer. Specific specifications for sub-GHz wireless communications are stipulated by the JJ-300.10 standard from the Telecommunication Technology Committee (TTC). Renesas has been working on developing a communications stack based on the A method of JJ-300.10 (specifications from the ECHONET Consortium and the Wi-SUN Alliance) from the start, and offers its efforts as an IP stack (figure 3, tables 5 & 6).
This IP stack supports 6LoWPAN, IPv6, ICMPv6, UDP, and other IP-based functions. PANA (Protocol for Carrying Authentication for Network Access) is supported for security for authentication, key generation, and so on. Although PANA requires relatively heavy processing such as hash calculation, a calculation library optimized for the RL78 or RX63N microcontrollers can be used to, for example, achieve route B communications processing performance even when operating an RL78/G14 at 8 MHz.
Table 5. RL78 Family Wi-SUN IPv6-R protocol stack
Table 6. RX600 Series Wi-SUN IPv6-R protocol stack
In Japan, HEMS (Home Energy Management System) devices that carry out energy management in homes have been anticipated to become popular since deregulation of electric power retailing in April 2016. Due to the adoption of the Wi-SUN communications standard for smart meters by Japanese electric companies, the use of the Wi-SUN Alliance's Wi-SUN standard for the 920 MHz band for communications between 1) power meters and HEMS devices and 2) HEMS devices and HAN (Home Area Network) is expanding. HEMS devices have two communication control systems in order to control two series of communications functions. Conventionally, these have all been controlled individually by software. Renesas has developed a dual stack to control two networks using a single communications control system. This dual stack supports the aforementioned MAC stack and IP stack.
Towards More Stable Communications
If the number of surrounding communication devices increases, the software processing load for discriminating addresses also increases. Renesas communication devices (RAA604S00 and RL78/G1H) have a built-in function for automatically discriminating two series of communication addresses. Thus, even if the number of surrounding communication devices increases, the two series of communication addresses can be discriminated confidently and without delay. As a result, the software processing load can be lightened, helping to avoid system instability stemming from erroneous reception or other problems.