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projects:hi-pi [2015/03/11 00:27]
darron 		projects:hi-pi [2017/03/23 05:34] (current)
darron [Appendix]
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-==== Hi-Pi high voltage programmer ====+==== Hi-Pi high voltage PIC programmer ====
  
 <wrap right> <wrap right>
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 </wrap> </wrap>
  
-This is an out of circuit (not ICSP) high voltage programmer for the Raspberry Pi.+This is an out of circuit (not ICSP) high voltage PIC programmer for the Raspberry Pi.
  
 Low voltage programming in-circuit is preferable but a high voltage programmer Low voltage programming in-circuit is preferable but a high voltage programmer
 is sometimes a requirement for older parts which offer no low voltage mode, or is sometimes a requirement for older parts which offer no low voltage mode, or
-to reset a device which has low voltage programming mode disabled in it's+to reset a device which has low voltage programming mode disabled in its
 configuration bits. configuration bits.
 +
 +=== News ===
 +
 +A bug may occur with this circuit in certain situations, please refer to the
 +appendix.
 +
  
 === Schematic === === Schematic ===
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 A switch is used to switch in and out a 9V zener. With the switch off a 12V zener is active which is to support older generation PIC micros whereas 9V is needed for more modern ones. Read the programming data-sheet of your target device to determine the correct voltage. If in doubt, start at 9V and see if it works. If programming or erase fails, switch to 12V operation. A switch is used to switch in and out a 9V zener. With the switch off a 12V zener is active which is to support older generation PIC micros whereas 9V is needed for more modern ones. Read the programming data-sheet of your target device to determine the correct voltage. If in doubt, start at 9V and see if it works. If programming or erase fails, switch to 12V operation.
- 
-The TELCOM driver will produce something close to 15V on it's output when activated, it's important to be careful with wiring here and appreciate that this is dangerous voltage for something like a Raspberry Pi. Be careful when connecting the input pin. 
  
 {{:projects:hi-pi.png?200}} {{:projects:hi-pi.png?200}}
  
 +The TELCOM driver will produce something close to 15V on its output when activated, it's important to be careful with wiring here and appreciate that this is a dangerous voltage for something like a Raspberry Pi. Be careful when connecting the input pin.
 +
 +Note: This is version 1 of Hi-Pi, version 2 will appear here later which will add some small improvements.
 === Pickle Microchip PIC ICSP === === Pickle Microchip PIC ICSP ===
  
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 PGDI=6 PGDI=6
 # PGM # PGM
-PGM=255+PGM=-1
 </code> </code>
  
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 Because this is an out of circuit programmer, we will now need to remove Because this is an out of circuit programmer, we will now need to remove
-the chip from the it's programming station and place it in-circuit to+the chip from its programming station and place it in-circuit to
 operate. operate.
 +
 +=== Appendix ===
 +
 +Thanks must go to Tomas Lorenc who has notified me a fix is required
 +for devices which have MCLR configured as an I/O. In this situation
 +a device is not brought out of reset and into programming mode due to VDD
 +being raised first. Here he presents a fix for this situation.
 +
 +{{:projects:hi-pi-mod.png?200}}
 +
 +For example, the PIC12F675 has this feature in it's configuration word.
 +
 +<code>
 +bit5
 +MCLRE: GP3/MCLR Pin Function Select bit(5)
 +1 = GP3/MCLR pin function is MCLR
 +0 = GP3/MCLR pin function is digital I/O, MCLR internally tied to VDD
 +</code>
 +
 +