Development Kit Analysis: Kit Takes Wi-Fi Halfway

Redpine Signals has assembled a kit that can help engineers andproduct designers include a Wi-Fi port in a product, and thus connect wirelessequipment to other networked devices or the Internet. I found the kit easy touse and it quickly detected and connected to a wireless router. Testing wouldhave taken less time, but the lack of clear instructions caused a delay. Iwould give this kit higher marks but for several warnings noted below.

Instead of designing its own kit, Redpine collaborated withRenesas to create a small Wi-Fi board that plugs into a Renesas RSKR8C25Starter Kit (provided). The latter kit includes a microcontroller board, characterLCD, emulator pod, software and a power supply. The separate Redpine boardsupplies an RS9110-N-11-22 wireless-device server module that complies with theIEEE 802.11/b/g/n specifications. The small module can operate with open or secureWi-Fi access points and it supplies its own wireless LAN stack. Software on theRenesas MCU board communicates with the Redpine board through either a serialport or with an SPI port. In an OEM product, you would buy RS9110-N-11-22modules and communicate with them from your own MCU using an AT-like commandset.

Because the kit came with a printed Renesas Quick-Start Guide(QSG) and CD but only a Redpine CD, I started with the Renesas information andinstalled the company's High-performance Embedded Workshop (HEW) tools. Afterworking through the Renesas instructions, LEDs on the MCU board flashed and atest message appeared on the LCD. So far, so good.

Next I examined the Redpine CD and printed its readme.txt filethat list the CD's contents: demo software, manuals, RS9110-N-11-22 moduleinformation and code, and another copy of the Renesas HEW tools. A RedpineQuick-Start Guide explains how to attach the Wi-Fi board to the MCU board andthen conduct an auto-connect test with a wireless router. I ran into twoproblems. First, the test required an open (unsecured) wireless access point,so I had to remove security from my lab network, which I disliked doing, but itseemed impractical to carry the boards, power supply and laptop PC to the localpizza place where they have open Wi-Fi access.

Second - and worse - by building and loading the Renesas LED/LCDtest program I had wiped out Redpine's pre-programmed firmware in the RenesasMCU. So, the plug-it-in-and-try-it "experience" stopped temporarily. TheRedpine QSG included information about a Manual Mode engineers can use tomodify some network information in the original firmware and load the newfirmware into the Renesas MCU. I followed the instructions but did not change the code and then loadedthe firmware into the MCU. That step restored the Redpine firmware and thecombined Redpine/Renesas boards detected my wireless router and provided an IPaddress. A Java program on the Redpine CD ran on my wireless laptop and let mecontrol LEDs on the Renesas board via a wireless connection.

The first paragraph in the Manual Mode instructions notes kitusers should only go through steps 1 through 16 in the Renesas QSG so theywon't overwrite the Redpine firmware. Good advice, but too late. Redpine shouldinclude this information on colored paper and mark it boldly "StartHere" or others will have the same problem I did, which wasted a lot oftime. That's my first warning.

After you turn LEDs on or off from a computer on your networkyou'll want to investigate other things you can do with the Renesas/Redpine kit.The Redpine "API Library for Renesas Microcontrollers" manualexplains how to use the Redpine application programming interface (API)operations for UART-to-module or SPI-to module communications and it includes Csource code for three such programs. The source code starts out simple enoughuntil you realize it pulls in many other files. The tcp_udp_app.c file, forexample, includes almost no code comments, and comment templates at the startof functions lack function names and descriptions. So, wading through the codeto try to understand it could become a time sink. That's my second warning.

Although Redpine notes its modules respond to an AT-like commandset, I found no documentation for such commands. The supplied API seems toapply only - at least so far - to Renesas MCUs. A close look at the AT commandmight give developers insight into how easy or difficult it might be to use theWi-Fi modules with non-Renesas MCUs. (I await instructions from the Redpinesupport people about where to find the AT-command-set information.)

I bet Redpine hopes engineers will buy its chips and modules sothey can get "on the air" quickly with Wi-Fi communications. But,without details about how to set up specific operations, what the variouscommands do, and how to use parameters, creating code for the Redpine productswill require a long climb up a steep learning curve. At the least, Redpineshould provide a basic skeleton communication program, a flow chart, an explanationof parameters, and even a check list of things to include in a basic program.Let's hope Redpine can give engineers this information soon. That's my lastwarning.

So although the kit worked well and performed as advertised, itmight not take engineers all the way to a complete Wi-Fi-based application.

Click herefor information about the RS9110-N-11-22 wireless-device server module.