LPCXpresso Click Shield and I2C

[radug]

Hello,

I recently bought an LPCXpresso Click Shield (https://www.mikroe.com/lpcxpresso-click-shield).
Trying to use it, I noticed that there seems to be something wrong with the I2C pins (A4,A5):

LPCXPRESSO_SHIELD.png (39.76 KiB) Viewed 1698 times

But if we look at the schematics for the LPCXPRESSO we see that the I2C pins are located on a different socket (J1):

LPCXPRESSO_SCHEMATICS.png (68.71 KiB) Viewed 1698 times

Schematics are here: https://www.nxp.com/downloads/en/schema ... RevC_1.pdf
Or here for LPCXPRESSO11U68:

LPCXPRESSO11U86.png (531.56 KiB) Viewed 1698 times

Same situation for LPCXPRESSO824 (but I cannot upload more than 3 pictures).
Schematics are here: https://www.nxp.com/downloads/en/schema ... Rev_B1.pdf

Am I missing something here or is not possible to use the shield with any LPCXPRESSO board?

Regards,
Radu G.

[filip]

Hi,

Thank you for noticing this, I have done a research regarding your issue.

The fact is that LPCxpresso boards has Arduino UNO pin-compatible shield connectors, but there are two variants/revisions of the Arduino UNO boards available - Rev2 and Rev3.
Difference between these two revisions regarding the shield pinout is that the Rev3 has I2C lines doubled - one pair is present on the same place as with Rev2 (maintaining the I2C compatibility on the mikroBUS scoket - checked with ohmmeter),
while the other pair is added at the top of the 1x8 header (present on Rev2) resulting in 1x10 header (present only on Rev3). I'm attaching both schematics.

Following the Arduino UNO, the NXP designed and redesigned the LPCxpresso boards so there are Revision A, B and C of their boards (I'm talking about V2 generation of LPCXpresso boards, see here https://www.nxp.com/design/development- ... SSO-BOARDS).

LPCxpresso boards Revision A and B conform to the Arduino UNO Rev2 pinout, while the Revision C of LPCxpresso boards conforms to the Arduino UNO Rev3 except they do not follow the I2C lines doubling like Arduino did on Arduino UNO Rev3, leaving the I2C lines only at one location (at the top of 1x10 connector) and omitting the I2C lines that should be tied to the mikroBUS.

In your case, with the Revision C, I can only recommend you to try manually to connect the I2C lines from the LPCxpresso board to the shield, I see no alternative I'm afraid.

Regards,
Filip.

[radug]

Hi Filip,

Well I can only say that I have A LOT of LPXPRESSO & FRDM boards and they all seem use the I2C lines at the top of 1x10 connector. Some even in Rev. B.

Here is what I mean (LPCXPRESSO11U68 - RevB):

LPCXPRESSO11U86_REVB.png (576.15 KiB) Viewed 1628 times

IMO a small switch (like the one used for UART/PRGM lines) would have saved the day.
Out of curiosity, when was your shield designed?

Regards,
Radu G.

[filip]

Hi,

Well I can only say that I have A LOT of LPXPRESSO & FRDM boards and they all seem use the I2C lines at the top of 1x10 connector. Some even in Rev. B.

Here is what I mean (LPCXPRESSO11U68 - RevB):

This revision has I2C lines (P0_4 and P0_5 pins) on both header connectors so you will have no issues when using this shield as the I2C lines will be connected to the mikroBUS

IMO a small switch (like the one used for UART/PRGM lines) would have saved the day.

Yes, this would be a nice feature, I will propose this to our developers.

Out of curiosity, when was your shield designed?

I will check this, but as far as I know this was done in cooperation with NXP.

Regards,
Filip.