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I've been working on a remote control made out of a PIC 16F57. The PIC will wake up on every keypress, send the IR code and go back to sleep.

the remote is working fine, unfortunately I forgot to tie the T0CKI pin to either Vdd or Vss so it's floating. On some remote I can see that the power consumption is quite high even when in sleep mode so I think is due to this floating pin. Even the datasheet says clearly that to reduce power consumption when in sleep mode the T0CKI pin should be tied to Vss or Vdd.

Is there a way to "disable" that pin or change something in the registers in order to prevent (or minimize) that high power consumption without modifying the schematic?

The problem is experienced only on some remotes, not all of them

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  • \$\begingroup\$ It's right next to Vdd, can you just bridge it or is this more than a one-off repair? \$\endgroup\$ May 28, 2015 at 12:24
  • \$\begingroup\$ of course I can. We are talking about 50-100 remotes. It's not that much effort. However, I wonder if there is some software-only workaround to it. Can the T0CKI pin be configured as output for example? \$\endgroup\$ May 28, 2015 at 12:31

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Unfortunately with T0CLK there is no way in software to connect it to anything because it is an input only pin. You will need an old fashioned hardware solution to fix the problem.

Note that the datasheet specifically says on page 9 - "Must be tied to VSS or VDD, if not in use, to reduce current consumption."

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  • \$\begingroup\$ yeah... I missed that line in the datasheet. Now my question is: why the problem occurs only on some remotes? Maybe the floating pin is more biased towards Vss or Vdd in some remotes and in some others it stays in the middle? \$\endgroup\$ May 28, 2015 at 13:22
  • \$\begingroup\$ I've observed similar problems with floating pins on the 16F84. It can be a bit random, and sometimes even gets triggered by a bit of noise near the pin. I think it just depends on the specific characteristics of the input FETs and where the pin is actually sitting while floating. \$\endgroup\$
    – Jon
    May 28, 2015 at 13:49

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