Fullscreen HTML5Med Res (??MB)HTML4

WIB FAQs The Web Server In a Box (WIB) project has been very popular and lots of kits have been built. Here we collect a number of frequently asked questions that may help anyone experiencing difficulties in building and setting up the WIB. We also provide the answers to some common technical questions and feature requests. By MAURO GRASSI Software Releases At the time of writing, the released firmware for the WIB includes versions between 5.30 and 5.40. Most questions in this article relate to versions 5.30, 5.31 and 5.32. Version 5.40 is the latest and fixes two problems with earlier versions (see later). It has been made available to the kit suppliers and is also available for free download from the SILICON CHIP website. Future batches of kits should contain the new firmware version (5.40) or later. This FAQ compilation refers to the original hardware of the WIB, which used the dsPIC33FJ64GP802 microcontroller. However, it is now possible to use the dsPIC33FJ128GP802 chip as well. This device is pin for pin compatible but has double the program memory. By using this new chip, it would now be possible to incorporate many new features, including an ethernetbased bootloader. This and other features will be considered for a future upgrade to the WIB. Common Setting-Up Questions & Problems Q I have changed a setting in the settings.txt file using a text editor but the setting does not seem to have changed in the WIB. Why is that? This can be confusing at first and is one of the most common traps that constructors can fall into. Basically, the settings are stored A 20  Silicon Chip in binary form in the values.dat file. The settings.txt file is only for the default values (if there is no values. dat file), as happens on the very first boot up. The WIB creates the values.dat file from the settings.txt file if it does not exist. If it does exist, it uses the settings stored in the values.dat file. This scheme made the firmware simpler because changes to settings can be stored easily in binary form but are more difficult to store in a human-readable file like the settings.txt file. However, the humanreadable file is useful for setting up the default values. In order to change the settings siliconchip.com.au to those in the settings.txt file, you need to first delete the values.dat file and then reboot the WIB. A new values.dat will then be created, with the settings taken from the settings. txt file. This is done by clicking the “Restore Defaults” button in the supplied default website (ie, you don’t have to switch the WIB off and then on again in order to reboot it). Q There is a csettings.txt file in the supplied default website, as well as the default settings.txt file. What is the csettings.txt file for? The csettings.txt file is generated by the WIB and should not be modified, as it has no effect on the settings of the WIB. The csettings.txt file is created by the WIB at runtime to store the current settings in a human readable form. This is used in the “Create Defaults” function, where the csettings.txt file is copied to the settings.txt file. A Q Should I retain the directory information when I unzip the contents of ewswebsite.zip to obtain the supplied website (available from the January 2010 downloads section of the SILICON CHIP website)? No, the files should all be unzipped into the root folder of the memory card disregarding any original path information stored in the zip archive. A Q A There is a file named 0711109A. hex in the supplied default website, what is this file for? This file contains the firmware image for the latest version of the WIB. It can be left on the memory card and will not affect the operation of the WIB or it can be deleted. It is a small file, so it will not take up much space on the memory card. Note that if it is left on the memory card, it can then be accessed like other pages served by the WIB. Q I am having trouble logging in to the WIB with the username and password as set in the settings. txt file. Alternatively, some setting in the settings.txt file does not seem to be being parsed properly. Why is that? There could be a number of reasons for not being able to log on A siliconchip.com.au to the WIB using the username and password as stored in the settings. txt file. First, as explained earlier, the settings.txt file contains the default values, not the actual values of the WIB. The actual settings are stored in binary form in a file called values.dat. If you wish to revert to the settings in the settings.txt file, you should delete the values.dat file and reboot the WIB as explained earlier. Additionally, when the WIB reads the values from the settings.txt file, it will only parse a line if it finds a newline at its end. So a setting may not be being parsed simply because there is no newline at the end of the line (this happened to a reader). Remember every entry in the settings.txt file should be on a separate newline-terminated line. So if you can’t log on with the username and password in the settings.txt file, it may be because the last line in the settings.txt file does not contain a newline. In the default settings.txt file supplied, the password setting is last. While the file supplied has a newline, if you change this line, the last line may no longer have a newline and so the password will not be set. Q The WIB seems to be working correctly but it cannot send emails. There is an entry in the log. txt file with a hexadecimal error code. What does this mean? The hexadecimal error codes shown in the log.txt file relating to sending emails are standard SMTP (Simple Mail Transfer Protocol) error codes. These are returned by the SMTP server that the WIB is connecting to. For example, if your ISP is Telstra, you would be receiving an error code from the Telstra SMTP server and likewise with Optus and other providers. The list of SMTP error codes can be found online. The “Email From” may also need to be set if you are using your ISP’s SMTP server and are sending the email to a foreign email address, specially to a Gmail or Hotmail address. If not set correctly, an additional error may occur because of some SMTP server anti-relaying rules to do with spam reduction. A The relevant error is 0x0227 (Error 551). We found this during testing with the Telstra SMTP server, for example. Changing the “Email From” field may solve this problem. Remember the “Email From” field is simply what is shown as the Sender when you receive an email from the WIB, so it is not a crucial setting. Note that SMTP settings for “Email Server User” and “Email Server Password” are only used if the SMTP server you are sending to requires authorisation. Most ISP SMTP servers don’t require this (so you can send anonymous emails when you have an internet account) but some do require authorisation. If the Email User and Password settings are set, the WIB starts an SMTP session by trying to authenticate with the server. If the SMTP server doesn’t require this, then it may terminate the SMTP connection before the email is sent, returning an 0x01F7 error (Error 503), even if the username/password is correct. To avoid this problem, remove the two settings from the settings.txt file, delete the values.dat file and reboot the WIB. Q When I try to log on to the WIB using its IP address from the address bar of my web browser, it loops continually without loading the home page. Why is that? When you type the IP address into a browser, without qualifying any extra path information, it assumes as default that you are requesting the index.htm file. The index.htm file provided with the default website for the WIB uses the refresh metatag to redirect to the home page, which is the home.cgi page. On some web browsers or on some versions of those browsers, this has the effect of looping continually without loading the page. Specifying the complete path (eg, 192.168.0.34/ home.cgi) rather than only the IP address should solve this problem. Alternatively, changing the contents of the index.htm page can solve the problem. A Q Can the microcontroller in the WIB be programmed using the dsPIC/PIC Programmer described in April 2010  21 the May 2008 issue? If not, how can it be programmed? No, the dsPIC/PIC Programmer cannot program the dsPIC33­ FJ64GP802. The latter microcontroller was not available at the time the programmer was designed and so is not supported. Instead, it is best to use a programmer like the PICkit3 from Microchip together with their free MPLAB software. A Q Can you give an example of what values are needed for connecting a straight 0-5V sensor to the analog inputs of the WIB rather than a 3.3V sensor as described in the original article? You will need to connect your sensor to a voltage divider to bring its output within a 0-3.3V range. This can be done by connecting a divider that divides by 5/3.3 = 1.52 (eg, 10kΩ and 20kΩ). You will then need to calculate the correct values for your sensor and enter them in the gradient and Y-intercept fields in the variables.cgi page of the default website. The instructions to calculate these values are in the original articles. A Q The LM317 voltage regulator used to derive the 3.3V rail for the WIB runs hot to the touch. Is this normal and how can the heat be reduced? It is normal for the regulator to get hot and so the original de- A sign specifies a heatsink. The higher the input voltage delivered by the plugpack the more heat that will be dissipated. To reduce the heat dissipation, you should use a 6V plugpack. Q Can the WIB take digital inputs? Can the WIB send an email notification when a digital input changes? For example, can the WIB send an email notification when a reed switch closes or opens? While nominally the WIB only accepts four analog inputs, they can also be used to accept digital inputs. If the digital input swings between 0V and 3.3V, it is easy to set the minimum and maximum values at about the middle of this range. However, the minimum should be below the maximum to allow for hysteresis. The WIB can then send emails when the state of the digital input changes. If using a reed switch, you do the same but use a pull-up resistor to the 3.3V rail or a pull down to 0V. If the digital input is not within a 0-3.3V range, you will have to implement some kind of level translation. This can sometimes be easily achieved by using an open collector output and a pull-up resistor to the 3.3V rail. A Q Can the digital outputs of the WIB be pulsed for a determinate amount of time? A Not with the current versions of the firmware, although this could easily be incorporated if sufficient program memory were available. You could have an extra variable (or four extra variables for independent control) to hold the pulse time in milliseconds and new commands to pulse the outputs. These are easy additions to the firmware but there is not enough program memory to make the modification with the original hardware. It is certainly possible with the 128KB version chip and may be incorporated in a new design in the future. If readers really want this function, they could delete parts of the code to make room for it. Q Can the WIB be used with Windows based FTP programs? In particular, can it be used with programs such as FileZilla? With versions of the firmware before 5.40 some FTP programs like FileZilla did not like the WIB’s response to the PWD command. This was fixed in firmware version 5.40 in response to a reader’s report. In any case, versions without this fix should still work with the recommended FTP command line Windows client, as explained in the original article. Note that the WIB is not guaranteed to work with other FTP clients because it does not support the full FTP command set. A USB Support & File System Storage Q A Are there any plans to make the WIB work with an NTFS file system? No, there are no plans to make the WIB support file systems other than FAT. As NTFS is primarily a Windows file system, you would lose the portability that FAT offers. Note that you can read FAT with either a Windows or Linux PC and with a Mac. Also, there is little appreciable gain in performance in going from FAT to NTFS for the WIB project (there is for a PC though). FAT is perfectly adequate for the WIB (it is limited to 2TB but there is not going to be an MMC/SD/SDHC 22  Silicon Chip memory card that can store 2TB any time soon!) It is true that there is also a single file size limit with FAT that would be much less restrictive with a newer file system like NTFS. However, the limit is around 4GB and we think this is more than adequate for the application. If you are going to serve a page of that size it will take a considerable amount of time using the WIB – it is a huge amount of data. There are also licencing issues with NTFS that are avoided with a FAT file system as used in the WIB (there are issues with FAT too). The FAT code used in the WIB is open source and the NTFS code would also certainly have a larger memory footprint. NTFS is suitable for modern operating systems running on PCs with abundant resources but it is much less suitable for embedded systems with few resources like the WIB. For all these reasons, FAT is a good choice as a file system for the WIB and for many other embedded systems. Q Can a USB flash drive be used to store website files for the WIB instead of using an MMC/SD/SDHC memory card? If not, are there any siliconchip.com.au plans to modify the WIB to do this? To interface to a USB flash drive would require implementing a USB host interface, including a supply to power the USB. The WIB does not have the hardware to do this. For this reason, it would not be viable to modify the WIB to support a USB flash drive. We believe a memory card is adequate for the application and has the advantage of being quite compact. USB flash drives are perhaps more easily transported and removed but in this application, we assume that the memory card will be seldom removed. A Q Are there any plans to make the WIB work with an external hard drive, either via a USB port or natively? No, there are no plans to change the WIB’s mass storage from its current medium. We believe that the current capacities that can be purchased in SDHC cards (up to 32GB) are more than sufficient for the applications that the WIB will be used for. While hard drives offer cheaper and larger storage capacities, the complexity of the interface rules it out for the WIB. The microcontroller has no native USB host support and there is no other hardware on the WIB to support connection to a USB device. Adding a native hard drive interface would be even more complex. A Added to this, a memory card uses less power and is more compact, reliable and faster than a hard drive. Q A Can the WIB be used with 3G wireless modems with a USB port (dongles)? No, since the WIB does not implement a USB host, it cannot be used with such 3G modems. The WIB can only be used with an ethernet connection. To be able to use a USB modem, you would need a USB host and the WIB has no such hardware support as it stands. However, there are 3G wireless modems which have an ethernet connection and you should be able to use such a modem with the WIB. Miscellaneous Questions Q Is it possible to put a slot in the external case so that the memory card can be removed or inserted without having to take the case apart to get at the card? When the design was conceived, we assumed that the memory card would only infrequently be inserted or removed, as files can be uploaded or downloaded using an FTP client. It would be possible to house the WIB in a different case with a slot that would allow easier access to the memory card. In fact, you could even use it in a freestanding manner without a case, or leave out one of the side panels if you use it with the originally specified case. A Q The RJ45 connector from Amphenol used in the WIB (CON2) has pins 4 & 5 and pins 7 & 8 each internally shorted and then connected via 75Ω resistors to a single 1nF capacitor connected to 0V. Would this cause problems if it were connected to a PoE (Power over Ethernet) system? Wouldn’t some of the 75Ω resistors be destroyed? The termination used in the WIB is the one recommended in the datasheet for the ENC28J60 ethernet controller (obtained from the Microchip website). The 75Ω resistors and the 1nF capacitor are for EMI reduction and ESD protection and the 1nF (2kV) capacitor connects to the metal shield of CON2 for this purpose. The RJ45 connector used in the WIB is not designed for PoE applications and it would be a problem if the PoE host simply applied power. But that doesn’t happen – PoE hosts test the resistance between the terminals before doing so. In other words, a device configured for PoE must have the correct resistance before it is supplied with power. Since the WIB doesn’t present the correct resistance, the PoE host will not (or should not) apply power to it (an RJ45 connector for PoE would add capacitors in series with the 75Ω resistors). A example, you could have the WIB send an email every time a certain sequence of serial data is received or send the serial data received in an email. When the firmware was written, program memory was at a premium and some features had to be dropped. The serial port functions for sending data and now taking up memory could perhaps be replaced with code for receiving data. A Serial Port Questions Q A Can data be logged from the serial port of the WIB? You cannot log data from the serial port using the current versions of the WIB firmware. However, you can log data from the four analog inputs to the SD card and email them to a nominated account. Q Is it possible to communicate in both directions with the onboard serial port of the WIB? siliconchip.com.au No, it is not possible with current versions of the firmware to receive serial data with the WIB. It would not be difficult to modify the source code to allow the WIB to receive data into a buffer or to write it to a file on the memory card, perhaps with network time information as well. You could also build in a serial server that would listen to serial commands and run functions, depending on the received data. For April 2010  23 Website Functionality Questions Q A Can the WIB firmware be easily modified to include support for PHP and ASP server-side scripting? No, it is not possible – the WIB supports only client side scripting. Server-side scripting is intended for more powerful PCbased or embedded servers but is not really suitable for the WIB. We cannot rule out some kind of serverside scripting for a future upgrade but it may not be on the scale of a full-featured language like PHP, simply because the hardware is not powerful enough. Q A Is it possible to use a typical LAMP (Linux, Apache, MySQL, PHP) installation with the WIB? No, it is not possible. Such installations are for full-featured PC-based or embedded servers that are much more powerful than the WIB. The WIB is not a full-featured server, nor does it have the speed or memory (or even hardware archi- tecture) to run such an installation. Q A Can the WIB support a website for online shopping using a shopping cart? No, the WIB does not support a shopping cart application. There are a number of reasons. First, it does not support server side scripting and second, it would not be ideal from a security point of view as the WIB does not support encryption either. Feature Requests Q A Does the WIB respond to ping requests? Does the WIB implement a DHCP client? No, the WIB does not support ICMP and will not reply to ping requests. Early versions of the firmware supported ping but that was dropped to make room for other features due to limited memory. DHCP client support was also dropped for the same reason. Q A How can the firmware be updated if there are future changes? Currently, the only way to do this is to use a PICkit3 programmer. This is because the WIB doesn’t have a bootloader which would allow its program memory to be rewritten with an upgraded version of the firmware via an ethernet connection. The microcontroller supports RTSP (Run Time Self Programming) but there was simply not enough program memory to implement such a feature. However, as stated at the beginning of this article, it is possible to use the dsPIC33FJ128GP802 chip instead of the original microcontroller. This latter device is pin-forpin compatible but has double the program memory. By using this chip, it would be possible to incorporate many new features, including an ethernet-based bootloader and we may make this feature available in a later version of the project. Q What are some of the feature requests that have been submit- 24  Silicon Chip ted by readers? Will they be implemented in the future? Several readers have modified the firmware so that it does not delete the variable log files on reboot and to immediately log the variables on reboot, without waiting for the first log interval to elapse. Some readers have also added extra digital outputs and inputs via extra hardware, although the four analog inputs can also be used as digital inputs. There are no plans at the moment to incorporate these features in the standard firmware for the WIB. A Q What are some of the feature requests that you have received from readers and which of those are viable? What other add-ons are possible? We have had many requests from readers for features. Among these are: (1) Better security, using encryption at least for the HTTP headers; (2) Support for server-side scripting like PHP; (3) Connection of additional sensors, including perhaps digital interfaces for sensors (eg, 1-wire Dallas); (4) Battery backed-up power supply, including a mechanism to monitor mains voltage; (5) Using the WIB for controlling a number of mains powered appliances (eg, to power cycle computers through the web server); (6) A bootloader to allow for easy firmware updates; A (7) Faster ethernet connection and WiFi (wireless) connection. The ones that we think are viable are (1), (3), (5), (6) and we could also add DHCP client support and ICMP support. Server-side scripting of some form could be incorporated but almost certainly not in the form of PHP, so we think that (2) is not viable. We think that (4) is too specialised and thus not viable. Note that many computers can be woken up using their LAN interface remotely (wake-on-LAN), so (5) would really only be for controlling mains devices other than PCs with a wake-on-LAN feature. Note that the Microchip TCP/IP stack is also fully integrated with WiFi support and Microchip also supplies the hardware for WiFi. As such, WiFi is also possible but would depart from the original design substantially. Again, although Microchip also now provide a 100Mbps ethernet controller, it comes in an SMD package which would thus also depart from the original design substantially, so (7) is probably not viable (it would be a new hardware project). When you exclude firmware features, there are also many other hardware add-on boards that could be designed. The WIB Time Display Module published in the February 2010 issue of SILICON CHIP is one such item and one reader has used an LCD rather than a LED display, with good results. siliconchip.com.au Source Code Requests Q I want to experiment with the source code. Are you going to make it available on your website? What software is required to compile the source code? What hardware is required to reprogram the microcontroller with a newer firmware version? The source code for the WIB was written in C and was compiled using the full version of the Microchip C30 compiler (kindly donated by Microchip). The full version allows all optimisations and makes the A code fit with the original hardware. The code will not fit if using the free version of the Microchip C30 compiler (at least at time of writing, with current versions of the compiler). The source code will not be made available on the SILICON CHIP website but has been released to many readers on a case-by-case basis with certain conditions (ie, the code can only be used for personal, non-commercial use). The free MPLAB software suite from Microchip (www.microchip. com) can be used as an IDE (Integrated Development Environment) and to program the microcontroller in-circuit using a programmer like the PICkit3 (also available online from Microchip). MPLAB also supports other programmers. The microcontroller can also be programmed on a breadboard or in a ZIF socket. Future versions of the firmware may include an ethernet bootloader to allow the firmware to be easily updated without using a programmer. correctly ask for login information for file extensions set to private, exposing a security risk. For example, the settings.txt file can be viewed without logging in (the settings cannot be changed, however). Version 5.40 fixes this problem. This problem can also be fixed by changing the default file permission to private (the default is public). This workaround works except that all files will then be private. If you want some to be public and some private, you will have to update the firmware. The other problem is more minor and is also fixed in version 5.40. It simply adds quotes around the PWD command reply of the WIB’s FTP server. This is necessary to prevent some FTP programs from reporting errors with the WIB’s response. Note that the command-prompt FTP client supplied with Windows can still be used with the WIB to transfer files to and from a PC. check your ISP’s terms to ensure that the WIB can be used with your account. In some cases, it may be necessary to get a business account or a static SC IP address. Known Bugs & Errata Q A Are there any known bugs and workarounds for the WIB? Yes there are two known problems with firmware versions that are fixed in version 5.40. The first problem occurs when using an IP address for the WIB other than 192.168.0.x, eg, a 10.1.1.x address. Most people will be using a 192.168.0.x address so this issue will not be apparent. If you assign an IP address other than 192.168.0.x, the WIB does not ISP Terms Of Use Please be aware that serving web pages may contravene your internet plan’s terms of use. You should Are Your Issues Getting Dog-Eared? REAL VALUE AT $14.95 PLUS P & P Are your SILICON CHIP copies getting damaged or dog-eared just lying around in a cupboard or on a shelf? Can you quickly find a particular issue that you need to refer to? Keep your copies of SILICON CHIP safe, secure and always available with these handy binders Available Aust, only. Price: $A14.95 plus $10 p&p per order (includes GST). Just fill in and mail the handy order form in this issue; or fax (02) 9939 2648; or call (02) 9939 3295 and quote your credit card number. siliconchip.com.au April 2010  25