how to do a chip erase on AT90S8515

i am new to embedded programming, so please be easy on me...

i designed a circuit board, got it printed, and used the AT90S8515 as m MCU. ive soldered the MCU, programming pins, and all of the other littl stuff on to see if it will program.

i am using the ATAVRISP MKII programmer, and AVR studio reports that i can communicate with the chip.

here is my problem: the Mode 3 lock bit is enabled (further programmin and verification disabled) and i have no idea how to fix that. th preserve EEPROM fuse is also set. the MCU came like this (i bought 10 they were sealed in the cut-tape, but they must have been shipped fro atmel like this)...

how do i get unlock this chip so i can write a program on it? ive got som test LEDs connected to the MCU and i started this project to teach myself.

last thing. the SPIEN fuse is ghosted out with a little red thing in th corner of the box and it is unchecked (Set to 0 i assume). is this how want it?

thanks a TON for anything you guys can help me with. im stuck and feelin pretty bad about this project since i could have potentially wasted a lo of time and money if the MCUs i bought aren't going to be programmable.

Reply to
bandtank
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That's strange. They should have been enabled from the factory. Anyway, that does not change the fact of lousy design by Atmel regarding locks and fuses. My complaint is JTAG, as well as ISP. If they are disabled, you have to high voltage parallel program.

Reply to
linnix

oh great :( i dont have the know-how or the resources to do that, and m MCU is already soldered down. this really sucks.

my circuit has nothing on it except the MCU, crystal, reset pull-u resistor, programming pins, and a test LED. could i solder wires to th MCU and use those to parallel program somehow? do i need to buy anothe programmar to do this programming? if there is an FAQ or guide to do thi i will read that instead of asking you guys 100 easy questions. im prett disappointed that atmel would force you to parallel program something tha is advertised as ISP. there shouldnt be a way to "break" it and not be abl to serial program anymore.

Reply to
bandtank

You need to isolate clock and reset and 20 other pins, unfortunately.

Yes, same here. I got some Jtag boards that cannot be programmed anymore, after previous jtag programming. Fortunately, they still run the last program that was programmed.

Reply to
linnix

You need to isolate clock and reset and 20 other pins, unfortunately.

Yes, same here. I got some Jtag boards that cannot be programmed anymore, after previous jtag programming. Fortunately, they still run the last program that was programmed.

Reply to
linnix

Be very sure that your ISP is clocked at less than 1/4 of the chip's clock. There's no reason for Atmel to have shipped chips with the fuses set that way but it's possible for the ISP to mis-read them if its timing is off. Check that you really have the clock oscillator or crystal running at the correct pins and expected speed and that the ISP's timing is correct. A read-back of the chip ID is a good check.

--
Rich Webb   Norfolk, VA
Reply to
Rich Webb

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