Here’s another “problematic” project, few years ago Me5htar bought some LED display modules on discount cialis fedex eBay, they could not be initialized, so he asked me to try to do something with them at least do the initialization and see if they work at all. Not only that none of my attempts worked, but soruce code that was in the manufacturers data sheet has not worked (with AVR uC). I even made board with PIC microcontroller from data sheet and websites for generic viagra tablets compiled theirs source, and again did not work!
After that I returned to the good old ATmega16 and connect communication pins to logic analyzer and found that “strobe” signal goes a bit too early, some controls would probably work, some not because it’s “timing” was on a fine edge between working or not. After I added a couple of cost cialis viagra NOP’s before calling “strobe” function all started working.
In one of the following posts I will write more about the displays and their controllers, with these LED modules are a Holtek’s HT1632 controller. Communication takes place over four wires, RD, WR and Data of all the sildenafil citrate generic viagra uprima modules are connected in parallel while each mode has its own CS. CS – Chip select signal selects display controller or display module that microcontroller will communicate with; other modules are in Hi-Z, a state of high impedance. DATA – the data pin over which serial data stream is written and read from the display controller (MSB bit first). The data is transmitted to compare cialis online display controlere by setting the MSB bit of transmitted byte on data pin, and then “strobe” WR pin (set to a logical one and then to zero, because these modules receive data on the rising edge of WR signal). Reading data from display is ciao buy now viagra url simmilar, only difference is that RD pin is “strobed” and data bit is read from data pin. This is the description of communication on hardware level, generic cialic vs cialis the entire communication is little bit complex, there are various registers … if you’re interested in more detail find a datasheet on the net and if you have any questions post them on forums or in the comment below this text, I will gladly help.
This firmware is made for ATmega 16 uC (microcontroller), a developement board I used on this project is “STK16 +” module purchased on eBay, display modules are connected as follows:
WR -> Port B1,
Dat -> Port B2,
Cs -> Port B0,
CS1 -> Port B4,
CS2 -> Port B5,
CS3 -> Port B6
without pull up / down resistors, etc., of course, display modules requires 5-volt power supply. The device shown in the pictures is powered from the USB port. On the RX and TX pins of viagra prices canada the uC is connected MAX232 level converter -> so development board can be connected to computer COM port and you can send commands and texts to display(s). If you do not have a COM port on your computer you can get a “USB to RS232 converter.
FREE TIP: When I was at Me5htar’s home i confiscated some kind of cable for mobile phones, cialis online online a href “CA-50″ which when you cut off the end that goes to get a cell phone, you get TTL Rx and Tx, which can be directly connected to the microcontroller, get one of these if you use uC often, these can be very helpfull, if you can not find it, please let us know.
To send a command via the COM port you need some kind of “terminal” program; most common on windows OS is “Hyperterminal”; there are many better programs available on the net. Baud rate should be adjusted to the 19200.
Apart from text entry, there some command available too, so if the “@” is viagra pills online first character, then the next character is command. For example:
“@ A” -> Clear display, delete the contents of all the displays,
“@ BN” -> fill the display, full display with byte “n” (n is any number, shown binary as column of 8 pixels)
“@ C” -> displays fill with random numbers, fill the display with the randomly generated numbers,
“@ Dan” -> Shift display, move the contents of one display to the right place or the main goals, according to the “n”-in which can be either 0 or 1 (for left or right)
If you have any questions or suggestions, feel free to comment or open a topic on the forum.
Developement board: Shematic