| ??? 07/15/09 11:35 Read: times |
#167322 - You schematic will not work for the P89V Responding to: ???'s previous message |
The POR (power on reset) initialization of ISP for P89V parts is different to P89C parts.... hence your schematic is wrong!
Run Flashmagic and click in help-> Manual--> Page 48 which describes the circuit for the P89V. The DTR line is used to toggle the RESET line! Summary of getting in to ISP after POR ========================================= 1. Use a UART friendly Xtals... like you have 11.0592 2. Just after POR the P89V looks for a 'U' character from Rx serial port (only looks for 400mS) 3. After receiving the 'U' the P89V invokes the bootloader. The problem with your circuit --> The is no way to synchronize a POR and sending a 'U' character within 400mS (this is what the flashmagic circuit does). P89V RESET Signal management ============================= You will have to manage the RESET signals coming from the MAX813 and the flashmagic reset circuit. Joe |
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