Mixed voltage interfacing with the Bus Pirate

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(Any voltage 1-Wire, I2C)
(Examples)
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Here's some examples of how to interface different voltages using the Bus Pirate.
Here's some examples of how to interface different voltages using the Bus Pirate.
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===3.3volts===
+
These examples assume you use the Bus Pirate on-board pullup resistors. If you use the Bus Pirate's on-board pull-up resistors, remember to connect the Vpullup pin to the circuit supply voltage. The Bus Pirate pull-up resistors are powered through the Vpullup pin.
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Interface directly with normal pin outputs.
+
-
===Any voltage 1-Wire, I2C===
+
Some modes (1-Wire, I2C) only use high impedance pin outputs
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The Bus Pirate can interface with 1-Wire or I2C at 5.5volts or less.
+
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Open collector buses like 1-Wire and I2C '''always use pull-up resistors'''.
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===3.3volts===
-
 
+
* Interface directly with normal pin outputs
-
If you use the Bus Pirate's on-board pull-up resistors, remember to connect the Vpullup pin to the test circuit supply voltage. The Bus Pirate pull-up resistors are powered through the Vpullup pin.
+
* No pull-ups or Vpullup pin connection used
===5.0volts===
===5.0volts===
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* Choose Hi-Z output type
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* Connect the Vpullup pin to the power supply of the 5volt circuit
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* The 5volts can come from the Bus Pirate or an external supply
===2.5volts===
===2.5volts===
 +
* Choose Hi-Z output type
 +
* Connect the Vpullup pin to the power supply of the 2.5volt circuit
 +
 +
===Any voltage 1-Wire, I2C===
 +
* The Bus Pirate can interface with 1-Wire or I2C at 5.5volts or less
 +
* Open collector buses like 1-Wire and I2C '''always use pull-up resistors'''
 +
* These modes have no output configuration, outputs are always HiZ

Revision as of 14:22, 20 August 2010

This will be an updated guide to using the Bus Pirate pull-up resistors to interface stuff at different voltages.

Contents

About

The Bus Pirate's on-board pull-up resistors can be used to interface electronics above and below the Bus Pirate's 3.3volt supply.

Read how the pull-up resistors on the Bus Pirate work.

Read our guide to pull-up resistors and high impedance pins.

Examples

Here's some examples of how to interface different voltages using the Bus Pirate.

These examples assume you use the Bus Pirate on-board pullup resistors. If you use the Bus Pirate's on-board pull-up resistors, remember to connect the Vpullup pin to the circuit supply voltage. The Bus Pirate pull-up resistors are powered through the Vpullup pin.

Some modes (1-Wire, I2C) only use high impedance pin outputs

3.3volts

  • Interface directly with normal pin outputs
  • No pull-ups or Vpullup pin connection used

5.0volts

  • Choose Hi-Z output type
  • Connect the Vpullup pin to the power supply of the 5volt circuit
  • The 5volts can come from the Bus Pirate or an external supply

2.5volts

  • Choose Hi-Z output type
  • Connect the Vpullup pin to the power supply of the 2.5volt circuit

Any voltage 1-Wire, I2C

  • The Bus Pirate can interface with 1-Wire or I2C at 5.5volts or less
  • Open collector buses like 1-Wire and I2C always use pull-up resistors
  • These modes have no output configuration, outputs are always HiZ