Mixed voltage interfacing with the Bus Pirate

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===3.3volts===
===3.3volts===
 +
<nl2br>Select output type:
 +
1. Open drain (H=Hi-Z, L=GND)
 +
2. Normal (H=3.3V, L=GND)
 +
 +
(1)> 2
 +
Ready</nl2br>
* Interface directly with normal pin outputs
* Interface directly with normal pin outputs
* No pull-ups or Vpullup pin connection used
* No pull-ups or Vpullup pin connection used
===5.0volts===
===5.0volts===
-
* Choose Hi-Z output type
+
<nl2br>Select output type:
 +
1. Open drain (H=Hi-Z, L=GND)
 +
2. Normal (H=3.3V, L=GND)
 +
 
 +
(1)> 1
 +
Ready
 +
SPI> W
 +
Power supplies ON
 +
SPI> P
 +
Pull-up resistors ON</nl2br>
* Connect the Vpullup pin to the power supply of the 5volt circuit
* Connect the Vpullup pin to the power supply of the 5volt circuit
 +
* Choose Hi-Z output type
 +
* Enable the on-board pull-up resistors
* The 5volts can come from the Bus Pirate or an external supply
* The 5volts can come from the Bus Pirate or an external supply
===2.5volts===
===2.5volts===
 +
<nl2br>Select output type:
 +
1. Open drain (H=Hi-Z, L=GND)
 +
2. Normal (H=3.3V, L=GND)
 +
 +
(1)> 1
 +
Ready
 +
SPI> P
 +
Pull-up resistors ON</nl2br>
* Choose Hi-Z output type
* Choose Hi-Z output type
* Connect the Vpullup pin to the power supply of the 2.5volt circuit
* Connect the Vpullup pin to the power supply of the 2.5volt circuit
===Any voltage 1-Wire, I2C===
===Any voltage 1-Wire, I2C===
 +
<nl2br>I2C> P
 +
Pull-up resistors ON</nl2br>
* The Bus Pirate can interface with 1-Wire or I2C at 5.5volts or less
* 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'''
* Open collector buses like 1-Wire and I2C '''always use pull-up resistors'''
* These modes have no output configuration, outputs are always HiZ
* These modes have no output configuration, outputs are always HiZ
 +
 +
 +
[[Category:Projects]]
 +
[[Category:Bus Pirate]]

Latest revision as of 00:55, 11 September 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

Select output type:
1. Open drain (H=Hi-Z, L=GND)
2. Normal (H=3.3V, L=GND)

(1)> 2
Ready

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

5.0volts

Select output type:
1. Open drain (H=Hi-Z, L=GND)
2. Normal (H=3.3V, L=GND)

(1)> 1
Ready
SPI> W
Power supplies ON
SPI> P
Pull-up resistors ON

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

2.5volts

Select output type:
1. Open drain (H=Hi-Z, L=GND)
2. Normal (H=3.3V, L=GND)

(1)> 1
Ready
SPI> P
Pull-up resistors ON

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

Any voltage 1-Wire, I2C

I2C> P
Pull-up resistors ON

  • 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