I have a DS89c450 which I wish to program and so far have had no success. I have no programmers, so I need to utilise the ISP capabilities. I have the crystal connected (16Mhz) as well as the power. The data sheet indicates that EA and RST need to be pulled up, and PSEN needs to be pulled down to enter programming mode. Can these be connected straight to VCC/GND or do they need to be connected through a resistor? If so, what size would suit?
By using USB to Serial, I no longer need a 232 transciever do I? That would only apply to programming through a conventional serial port wouldn't it?
Once hardware issues are solved, I need to be able to program the chip. I have installed Kiel with C51 addon. I believe this is all I need to write the program. Following this, how will I write the software onto the chip? What software will I require to do so?
Whilst there are some tutorials online, they all provide basic information, not enough for a beginner. I'm hoping that any answers will be detailed enough to assist other beginner 8051 people like myself.
Best Answer
RST needs to be pulled up, EA and PSEN need to be pulled down. Whilst advisable, it is not always necessary to insert resistors here. Doing this removes the need for the HC125, opting instead to do it manually. To then use the chip, these three steps need to be undone as they apply only to programming.
Yes, USB to serial (Provided it is of the 5v TTL type, as opposed to the conventional rs232 found in a computers serial port) removes the need for the 232A transciever. This is only required for the computer Serial ports due to their different logic level.
Keil C51 is suitable to programming for the chip, although other packages are available. To flash the chip, the best software to use is the manufacturer supplied MTK which can be downloaded off their website (with a bit of searching). Whilst this software is designed for set serial ports and baud rates, custom ones can be used although compatibility is not allways assured. Check the USB to serial chip for specifications.
To those using a 16Mhz crystal, the only baud rate I could get to function was 16667 on a CH340g USB serial to chip.
I sourced most of this information off the following link: http://www.edaboard.com/thread27473.html