flashmagic handshaking circuit

[marcus]

i was wondering if it is vital to have the DTR and the RTS hooked up for the handshaking signal. if i dont have these hooked up will i have a problem with the status byte been set to zero when i reset the chip? thanks in advance

[Andy Ayre]

If you turn off the option in Flash Magic to use DTR and RTS, then they do not need to be connected - Flash Magic will ignore their states.

If the status byte is zero and you reset the device then you must ensure that you can get back to ISP mode. How you can do that depends on which device you are using, so check the datasheet. In short:

Most non-LPC9xx devices: attach a switch to /PSEN
LPC9xx devices: enable serial break detect in your code and send a break condition from Flash Magic.

Also you can use Erik Malund's NoTouch method. There is a link to his document on the Flash Magic web page near the bottom.