Archive for category Electronics
Enabling telnet on Netgear EVA8000 Digital Entertainer
Posted by andre in Electronics, Home Automation on February 6th, 2008
The Netgear EVA8000 Digital Entertainer has a telnet daemon installed, but by default it is disabled. During bootup the startup script for the telnet daemon examines the contents of /etc/utelnetd.conf and starts the telnet daemon if the contents is set to “ENABLE 1″
Once telnet is enabled you can log into the system with the username “EVA8000″ and the password “Netgear”.
There are two ways to do this depending on which firmware version you are running.
If you’re still using the 1.2.x series of firmware you can use the built-in menu options that allows saving and restoring settings to modify this file.
The steps to accomplish this is documented by flusk on http://mpcclub.com/modules.php?name=Forums&file=viewtopic&t=13503
- Create a trial settings backup, using the Supervisor->Advanced Setup->Backup settings option
- Confirm that a file was created in the location you’ve set for the EVA to store its library on. The file will be in the backup directory
- Create a new file, called utelnetd.conf, in a directory called etc in a temporary location
- Change the contents of this file to contain a single line “ENABLE 1″ (without the quotes)
- Create a tar archive of this file including the etc directory
- Copy the tar file to the EVA Backup directory
- On the EVA8000, restore the settings from this file.
- Once the EVA has restarted telnet will be enabled and you can log in with username “EVA8000″ password “Netgear”
If, however, you are using one of the later beta firmware versions then the Backup settings option has been removed and you can no longer use this method to enable telnet.
To enable telnet on the newer firmware versions involve editing the firmware image to make the same change as above, changing ENABLE 0 to ENABLE 1 in the utelnetd.conf file.
I posted this same method on the Netgear Beta forums and it has been confirmed to work by others. (http://forum1.netgear.com/showthread.php?t=20991&page=2&p=95783)
- Split the FW image into three parts. A 32 byte md5 header, the bootloader+kernel and finally the jffs2 image. If you’re using the same FW as me (V2.1.16IS.IMG):
- Edit the jffs2 image with bvi and change the ‘ENABLE 0′ to ‘ENABLE 1′ inside the inode for dirent utelnetd.conf (Near offset 0×5cfd8 of the jffs2 image).
- Re-run jffs2dump -c on the new image. This will complain and say that the block now has an invalid CRC.
- Luckily it also prints out what the expected CRC should be.. so, make a note of this and update the crc (77 C7 E9 3E should be changed to 36 F6 F2 27 at offset 0×5CFD0 in the jffs2 image).
- Re-run jffs2dump again to make sure its consistent
- Combine the extracted bootloader+kernel with the new image and calculate the new md5sum:
- Create a new file with the ASCII portion of the md5sum in it, making sure it is exactly 32 bytes long (no newline)
- Stitch everything back together:
FW=EVA8000_V2.1.16IS.IMG dd if=$FW of=crc bs=1 count=32 dd if=$FW of=bootkernel bs=1 skip=32 count=$((0x210000)) dd if=$FW of=jffsroot bs=1 skip=$((0x210020))
cat bootkernel jffsroot_mod > tempimage md5sum tempimage
cat newcrc bootkernel jffsroot_mod > telnet_enabled.img
Note that some of these steps can be skipped because the CRC of the JFFS2 inode will usually be the same across image versions because the contents doesn’t change. The steps are only provided for completeness. In reality all you would have to do is edit the original image, change ENABLE 0 to ENABLE 1, change the JFFS2 CRC (which will be the same values as above), strip off the first 32 bytes of the new images, re-calculate the md5sum and insert it at the start of the file.
Nokia 3310 LCD Driver JAL PIC Library
Posted by andre in Electronics on March 29th, 2004
[An old project I moved from my previous website]
This JAL library includes functions for controlling the Nokia 3310 LCD (PCD8544 controller) and also a 5×7 font.
Currently the table used only works on 16F, but should not take much to modify it to work with 18F PICs.
It only uses 5 IO pins, so a smaller PIC could be used. The font however takes up a lot of ROM (the example program’s code size is 1305). If the text print functions (and the font) is not used it is of course much smaller, but also much less useful
.
Download: Nokia 3310 LCD JAL Driver - A JAL Library to drive the Nokia 3310 LCD with a PIC. * example_lcd.jal - An example program, the output of which you can see in the photo below * nokia_lcd_p.jal - Include this first, and modify it with the pins you are using to connect * nokia_lcd.jal - The main jal library * font_5x7.jal - The 5x7 font, include after nokia_lcd.jal since it uses functions in there
Sorry for the quality of these photos. I’m blaming my digital camera, but it is most likely due to a bad photographer.
On the right is my DIY Wisp628. The interface board between the LCD and the PIC consists of two caps (required for the LCD controller), a few 1K resistors in series with the datalines, and a LM317 to regulate the 5V down to 3V which the LCD requires.
Both normal and ‘inverted’ printing functions are available. The clips and tape holds all the pieces of the LCD together. In my haste to see how the connections are made I broke all the plastic holding pins.
For further reading about the display and microcontrollers, please visit the following sites:
- Electronic Projects <for you> – Various PIC based projects using a Nokida 3310 LCD with HI-TEC PICC and CCS source
- Microsyl Nokia LCD Library – An LCD Library for the AVR microcontroller written in C
- Berty’s Page – Information about lots of types of phone LCD’s including Nokia and Ericsson with sample PIC code for PIC16F84A in ASM
- serdisplib pcd8544 based displays – Connecting a PCD8544 based display to a PC Parallel port including connection diagrams
- Olimex LPH7366 Project – A Nokia LCD project for ARM processor with ASM source
- Nokida 3310 LCD – A Photo showing the dimensions of the display and a link to download the datasheet
- PCD8544; 48 x 84 pixels matrix LCD controller/driver datasheet - The LCD controller used in the Nokida 3310 Display
LM75 Temperature Sensor with 7 segment display output
Posted by andre in Electronics on March 24th, 2004
[An old project I moved from my previous website]
This is a test project built hastily on a solder less breadboard. It uses a LM75 to read the current temperature via I2C and displays the result on three 7 segment displays. It uses a PIC16F628 with an internal 4 Mhz clock.
The program was created using JAL
Note the LM75 is a surface mount device, so I had to solder wires onto it to use it on the solderless breadboard.

LM75 Temperature Sensor on breadboard
Sorry for the bad quality photo. The stuff on the left is a 5V voltage regulator and not shown on the schematic below.
Component List
Part Value Device Package Library Sheet D1 7SEG-CA 7SEG-13 special 1 D2 7SEG-CA 7SEG-13 special 1 D3 7SEG-CA 7SEG-13 special 1 IC1 PIC16F628 PIC16F628 DIL18 microchip 1 IC2 LM75 LM75 SOP-8 andre_lm75 1 Q1 BC557C BC557C TO92-EBC transistor-pnp 1 Q2 BC557C BC557C TO92-EBC transistor-pnp 1 Q3 BC557C BC557C TO92-EBC transistor-pnp 1 R1 12K R-EU_0207/7 0207/7 rcl 1 R2 12K R-EU_0207/7 0207/7 rcl 1 R3 1K R-EU_0207/7 0207/7 rcl 1 R4 1K R-EU_0207/7 0207/7 rcl 1 R5 1K R-EU_0207/7 0207/7 rcl 1 R7 220 R-EU_0207/7 0207/7 rcl 1 R8 220 R-EU_0207/7 0207/7 rcl 1 R9 220 R-EU_0207/7 0207/7 rcl 1 R10 220 R-EU_0207/7 0207/7 rcl 1 R11 220 R-EU_0207/7 0207/7 rcl 1 R12 220 R-EU_0207/7 0207/7 rcl 1 R13 220 R-EU_0207/7 0207/7 rcl 1 R14 220 R-EU_0207/7 0207/7 rcl 1
In case you are like me and couldn’t find the pinouts for the sevent segment display, here they are:
Download the project here: LM75 Temperature Sensor Project - LM75 Temperature Sensor with 7 segment display output. Uses a PIC Controller. This project includes the JAL source code, a compiled hex file and a schematic.
PIC Binary Counter – A JAL Test
Posted by andre in Electronics on March 20th, 2004
This sample project uses a PIC16F628 and 8 LED’s to count in binary. Four switches are used to change the direction and speed of the counter.
The program was created using JAL.
The project is available for download here: JAL Binary PIC Counter - A JAL Project to count in binary on 8 LED's and 4 switches to change the counting behavour. Project includes JAL source, compiled HEX file and schematic






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