Post by thread:PIC 16C84 RS-232 In Circuit Programmer...

Hi Antti, I tried 2.2 Kohms and a parallel cap 100 nF but didn't work. The only way I got it working on two diferent PCs was with 4.7 Kohms. I'm doing In Circuit Prpgramming with a very simple modification to the Cheap (Or should I say inexpensive - Great value low price - ) RS-232 Prog. I programmed (ICP) about 50 times three 16C84, read/verified and erased them with no problem. Didn't blow any 16C84 (Yet... ;-) ) The circuit mod. is as follows: External VCC (+5V) thru 1N4148 to VDD (P14). External VCC (+5V) thru 1N4148 to MCLR (P4). Join VDD (P14) to RTCC (P3). TXd to VPP (RTCC) (P3) thru 2.2 Kohms DTR to RB7 (P13) thru 4.7 Kohms CTS to RB7 RTS to RB6 thru 22 Kohms. Rest of the circuit (RS-232 Power supply) as in the original, with 5.6 V Zener. Clock circuit is as usual. Another intresting thing is that as I can't get 16C84-10 here in Argentina, I'm using a 7.159090 Mhz Xtal with a 16C84-04/P. Tried 4 and all of them work OK. In my circuit RB6 and RB7 are dedicated to the programmer. You can program & erase while VCC is on and see instantly what's happening. To Read/Verify/Blank Check you have to turn of VCC. Any idea to leave VCC on all the time and be able to Read/Verify ? Didn't try PIP-02 V 1.02 Any new version to FTP ? :-) --- E-mail: spam_OUTmikeTakeThisOuTspeed.satlink.net Mike Binstok LU1DIU Buenos Aires ,Argentina

>I tried 2.2 Kohms and a parallel cap 100 nF but didn't work. >The only way I got it working on two diferent PCs was with 4.7 Kohms. Yes, the input impedance of DTR varies on different PC's. >Any idea to leave VCC on all the time and be able to Read/Verify ? Yes. This is the schematic for my PIC16C84 Module (without oscillator circuit). Programming can be done in circuit, if RB6/7 aren't connected to any high load. Otherwise I'm removing the module for programming. Supply voltage must be turned on, if the connected circuitry draws power from Vdd. The 2k2 / 4k7 between DTR and RTS is placed inside the SUB-D case, therefore removing the programming connector removes the load and RB6/7 will be free for use. TxD --------------------------*---------------------I I I --- I I I 2k2 I I-------I I I I +6.5 *-I 78L05 I-----I --- I I I-------I I I --- I I I --- I I 10k I I I \ / I I I100n I I --- 47k --- --- I I I -- I _____ --- I *---------*----------*--I I----*-------------- Reset I I I I I -- I I-----* I + /--- I I I --- / / \ 5V6 I I I --- 15u --- I I I I I I 14 I 4 I I I I--I----------I---I I I I I Vdd Vpp I I I I 5 I I GND -------*---------*---------*-------I Gnd I I I PIC 16C84 22k I I -- 12 I I RTS ---I I----------------------------I RB6 I -- I I -- 13 I I DTR ---I I---*------------------------I RB7 I -- I I I 2k2/ I I-----------------I 4k7 I CTS ----------I - Erik