subject: How To Unlock The Locked Dm500s? Knowledge About Jtag Serial Port [print this page] If your DM500S is locked, you cannot enjoy the satellite programs anymore. How can we deal with this problem? We can use the JTAG to rewrite the operating system on DM500S. This is the only way to save your machine. There is a named J61 16-pin port on the circuit board; this is the JTAG serial port.
Before we repair the machine, we should know the general information about JTAG. JTAG is an international standard about PCB and IC chips which was formulated by the Joint Test Action Group in 1985. It was modified to an IEEE standard (IEEE 1149.1-1990) in the year of 1990. With this standard, we can do Boundary Scan or Troubleshooting on the circuit made of CPU, DSP, CPLD or FPGA. The basic principle of JTAG is that it delimited a Test Access Port inside the board and then use the special JTAG testing tools to test the inside nodes of the circuit board. JTAG equipments can test whether the chip works well or not; it can also visit all the equipments on the bus of CPU, such as FLASH, RAM, if TCK is on a normal status.
If the company uses the JTAG to program the chips, it can achieve In-System Programmable. This will help the company to accelerate the velocity of production. So it is widely used in the board producing systems and software loading systems. Almost all the satellite receivers have the JTAG serial port as well.
There is a parallel port DB-25 on computer. This port is developed form the Centronics printer port and supports the standard of IEEE 1284. Before we can attach the board to the DB-25 port, we should have a JTAG transport board first.
Now, we weld the 6 wires of the board to the J61 JTAG port first. Then connect the board to the DB-25 port. Open your computer, download the DREAMBOX BOOTLOADER software. Open the jtag_windows.exe file under the dreamboxbootloader catalog. Then you will see the interface of DreamFlash for Windows v0.1. Click on the Connect button and turn on DM500S. Then you ought to copy the BIN files into the rewrite catalog and rename it to BLIMG. Remember, you should make the BIN file suitable for you Low Noise Block. Then, you click on Write and when you see Finished on your screen, you have done it.
Remove the JTAG wire and restart the DM500S, if the green light on the front board is on, you can continue to rewrite the system IMG using the RS-232 port or the Ethernet port.
