It was an idea to isolate the icd2's MCLR from target's MCLR during idle state. But the idea was wrong, the program already runs, when MCLR raises to the required level (when the Vpp was connected through 4066). So i have removed this jumper in my next schematic.X4 is a jumper to select what?
I have placed these jumpers to adjust the Vpp voltage. You can select 4 voltage levels with 4 combinations of these jumpers. These jumpers are replaced with digital pot.What is X2 and X3 meaning?
In my last schematic you can see the tolerances. Others are not critical, you can use 10% resistors.There is any limitation in tolerance on any component (1% or it's ok with 5%-10%)??
Why do you use 74hct125 and 74hc126 buffers connected parallel? It doesn't make any sense.
Thirdly, what for are these additional resistors for these buffers? When I look at V1.1 or v2.3 version on www.mcu.cz there is no need for such a combination. And this version from chechish site works perfectly, I made it (v1.1).
I have M74HC4066B1 from ST Microelectronics. You can use MC74HC4066 or MC14066B from Motorola or CD4066.togarha said:And what about 74hc4066 power supply?? It is connected to Vpp, and the datasheet says that the maximum power supply is 10V. Do you have a 74hc4066 or a cd4066??
I have tested it with 5V devices at lower voltages. Works fine up to 2V.togarha said:Have you tested it with a 3v3 device? I'm waiting for my explorer16 board, then I can start to build my ICD2...
The buffers are already in the chip. It's usage doesn't cost anything.szlovak said:Why do you use 74hct125 and 74hc126 buffers connected parallel? It doesn't make any sense.
You can simply replace the LT1172 with MC34063. Both has the same feedback voltage, practically you need to change only the pin connections. In my country LT1172 is more available.szlovak said:Secondly, what for do you use LT1172 instead of MC34063 ? MC34063 is cheaper and has enough power.
In my previous post i have answered this question.szlovak said:Thirdly, what for are these additional resistors for these buffers?
Have you tested the circuit on www.mcu.cz with target running at 2V? Buffers and these complications are required for low voltage devices. You need to make bidirectional level translators with parts available in any shop. There are simple level translators for ex. at TI, but you can't find it in local stores.szlovak said:When I look at V1.1 or v2.3 version on www.mcu.cz there is no need for such a combination. And this version from chechish site works perfectly, I made it (v1.1).
ICD2 doesn't place these pins to High impedance on idle state. If you want to use icd2 for programming only, and target's PGD and PGC pins are used in the target board as outputs, then the target can't drive these pins to H or L state, because, icd2 forces it to one state. When the jumper is in the right state, then icd2's pins and target's pins are connected only when the MCLR is near Vpp.togarha said:I think is a jumper to have always conected PGC & PGD to ISP_PGC & ISP_PGD, or to have it controlled, but, there is any problem to have it always controlled?
Increments and decrements.togarha said:How feedback power control works? pic puts an exact value in digital pot or increments and decrements its values??
Yes, i agree.togarha said:I think that resistors in feedback are not necessary to are 1% tolerance...
Nothing.pingouindunord said:What are the differences between icd2's Vpp (DG411) and pics's Vpp (BC557, BC547 and 1N5819)
Yes, the buffers are necessary for targets running at lower voltage.pingouindunord said:Potyo is it really necessary the buffer on your schematic?
In original ICD2 RA3 pin monitors +13V line while RA1 monitoring Target VccWhy do you connect 877-RA1 to 877-RA3, do the pins need the same voltage at the same moment?
You select cap value based on crystal requirement.Is it important the values of the cap connected to the quartz (22pF 27pF 33pF)?
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