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projects:hi-pi [2017/01/12 22:44] – external edit 127.0.0.1projects:hi-pi [2017/03/23 05:34] (current) – [Appendix] darron
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 to reset a device which has low voltage programming mode disabled in its 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.
  
  
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 the chip from its 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>
 +