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interfaces:level [2017/01/15 02:48] – [I2C converter] darroninterfaces:level [2024/07/10 12:29] (current) – external edit 127.0.0.1
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 ==== Level conversion ==== ==== Level conversion ====
 <wrap right> <wrap right>
-{{:interfaces:level1.jpg?200}}+{{:interfaces:level4.jpg?200|I2C}}
 </wrap> </wrap>
  
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 on a breadboard is to use a pre-built adapter. on a breadboard is to use a pre-built adapter.
  
-Two of the more popular types found at places like eBay +Two    popular types found on eBay 
-are two channel bi-directional I2C level converters and four+are the two channel bi-directional I2C level shifters and the four
 channel general purpose converters. channel general purpose converters.
  
-=== I2C converter ===+=== I2C level shifter === 
 +<wrap right> 
 +{{:interfaces:level1.jpg?200|Pickle Microchip PIC ICSP}} 
 +</wrap>
  
-These devices contain two mosfets with pull-ups resistors in the+These devices contain two mosfets with 10K pull-up resistors in the
 arrangement specified by the Philips I2C interfacing application note (link below). arrangement specified by the Philips I2C interfacing application note (link below).
  
 They also have an additional component which is a 3V3 LDO voltage regulator. This addition is to allow a 5V device to directly interface with a 3V3 device and also power it. They also have an additional component which is a 3V3 LDO voltage regulator. This addition is to allow a 5V device to directly interface with a 3V3 device and also power it.
- 
-The LDO has only been tested to drive an LED and it's not known whether the LDOs present are genuine and can be relied upon. 
  
 Although marketed for I2C they can be used for anything that demands two channels of bi-directional voltage level conversion. Although marketed for I2C they can be used for anything that demands two channels of bi-directional voltage level conversion.
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 There is a speed impact when using these device which have a slow rise time. For example, when using [[:projects:pickle|Pickle Microchip PIC ICSP]] it was found that raising the SLEEP configuration value to 8 was necessary. There is a speed impact when using these device which have a slow rise time. For example, when using [[:projects:pickle|Pickle Microchip PIC ICSP]] it was found that raising the SLEEP configuration value to 8 was necessary.
 +
 +=== General purpose 4 channel ===
 +<wrap right>
 +{{:interfaces:converter3.jpg?200|Pickle Microchip PIC ICSP}}
 +</wrap>
 +
 +These general purpose bi-directional devices feature four mosfets in the Philips application note arrangement with 10K pull-ups.
 +
 +== Pinout ==
 +
 +<code>
 +         HV4       LV4
 +         HV3       LV3
 +         GND       GND
 +HIGH VCC HV        LV  LOW VCC
 +         HV2       LV2
 +         HV1       LV1
 +</code>
 +
 +[[:projects:pickle|Pickle Microchip PIC ICSP]] was found to be more reliable when raising the SLEEP configuration value to 2 with this adapter.
 === Resources === === Resources ===
  
-[[http://www.nxp.com/documents/application_note/AN10441.pdf|Level shifting techniques in I2C-bus design]] +{{downloads:AN10441.pdf|Level shifting techniques in I2C-bus design}}