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Forum Index : Microcontroller and PC projects : I2C on UBW32 - which pins?
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| Decoy Senior Member  Joined: 02/08/2019 Location: DenmarkPosts: 109 |
Hi guys I just want to make sure - if I want to use I2C on my UBW32-based MaxiMite, am I correct in assuming that A2 and A3 should be used as SCL and SDA, as stated in the Colour Maximite on the UBW32.doc? Do I still need 10K resistors to 5V from SCL and SDA, or anything else? Thanks, Nicholas |
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TassyJim Guru  Joined: 07/08/2011 Location: AustraliaPosts: 5901 |
A2 and A3 are used for the RTC. From the CMM manual: "When enabled the I2C function will take control of the external I/O pins 12 and 13 and override SETPIN and PIN() commands for these pins. Pin 12 becomes the I2C data line (SDA) and pin 13 the clock (SCL). Both of these pins should have external pullup resistors installed (typical values are 10K for 100KHz or 2K for 400 kHz)." and from the Colour MMBasic on the UBW32 Board Implementation Manual Pin12 is A15 and Pin13 is A14 While the RTC module used was 5V, most I2C will be at 3.3V so the pullups will be to 3.3 not 5V Jim VK7JH MMedit MMBasic Help |
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| Decoy Senior Member Joined: 02/08/2019 Location: DenmarkPosts: 109 |
Thanks Jim So A2 and A3 can only be used for the RTC, even if one chooses not to employ the RTC. Did I read something about the 100KHz being more stable than 400KHz? Should I choose the former? Thanks again! |
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| TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 5901 |
400kHz is OK for short leads but it is really a case of try it and see. VK7JH MMedit MMBasic Help |
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| Decoy Senior Member Joined: 02/08/2019 Location: DenmarkPosts: 109 |
Okay, thanks! |
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