LPC MicrocontrollersのトピックRe: LCP1778 I2C timing question

LCP1778 I2C timing question

amandalin — Fri, 17 Mar 2017 14:07:32 GMT

LPC1788 I2C1 output can not meet the requirements of PCA9713'tHD;DAT timing,PCA9713'tHD;DAT timing need less 300ns,can you help me confirm LPC1788 solve probelm with software?or have others method?

Re: LCP1778 I2C timing question

Hui_Ma — Wed, 22 Mar 2017 00:45:49 GMT

I had done a test with LPC1788 Developer board using I2C1 with on board EEPROM.

I measured the SCL signal with SDA signal at falling edge with scope:

The I2C1_SDA signal falling edge is after I2C1_SCL signal falling edge, which the I2C communication as expected.

And the LPC1788 datasheet I2C-bus Dynamic characteristic also with below description:

My understanding about note 4 is to avoid the SCL signal with very slow falling edge and make sure SDA signal still hold during SCL falling edge. The SDA signal hold time was internally provided.

The LPC1788 I2C module should work with PCA9713 without any problem.

Wish it helps.

Have a great day,
Ma Hui
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

Re: LCP1778 I2C timing question

amandalin — Wed, 29 Mar 2017 08:31:00 GMT

Dear Hui_Ma:

Ok,Thanks for you reply.

But customer have a question about PCA9513 in this case,when test I2C sequence(SDA and SCL sequence),he find I2C output sequence(tHD;DAT<0nS),can you help how do sovle problem

The attached is tHD;DAT waveform of I2C output,pls check it

Thanks

Re: LCP1778 I2C timing question

Hui_Ma — Fri, 07 Apr 2017 04:56:51 GMT

Hi Amanda,

First of all, sorry for the later reply.

I checked attached PCA9513A schematics, could you tell us the above scope measurement point at SCLIN/SDAIN or at SCLOUT/SDAOUT pins?

Have you tested to remove the PCA9513A chip and measure the LPC1788 I2C module output signal with 4.7K ohm pull-up?

Have a great day,
Ma Hui

-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

Re: LCP1778 I2C timing question

amandalin — Fri, 07 Apr 2017 06:04:06 GMT

Hi hui_ma:

sorry ,i forget tell you that customer test piont is 30%CLK to 70%DATA ,times is -14ns,

Customer remove the PCA9513A chip ,LPC1788 I2C output is ok

Customer use LPC1788+PCA9513A,LPC1788 I2C output(PCA9513A input) is ok,but PCA9513A I2C time is <0ns(-14ns)

Do you have give your mobile phone or telephone?

Application :Server

Re: LCP1778 I2C timing question

Hui_Ma — Tue, 11 Apr 2017 06:05:07 GMT

Hi Amanda,

So, the PCA9513A output I2C time with above mentioned issue, right?

For the private info protection, if you need one to one service, I would recommend you to submit a case in our service system.

Please following below link to submit a service request to us, thank you.

https://community.nxp.com/docs/DOC-329745

Have a great day,
Ma Hui

Re: LCP1778 I2C timing question

amandalin — Fri, 14 Apr 2017 14:34:13 GMT

ok ,i want to discuss about this question

the PCA9513A output I2C time with above mentioned issue, right?

YES,That's the problem,can you help confirm this question how effect about system?

if customer use LPC1788+PCA9513A,Whether there is an impact?

thanks

Re: LCP1778 I2C timing question

Hui_Ma — Mon, 17 Apr 2017 06:39:50 GMT

Hi Amanda,

Could you try to modify PCA9513 external circuit related capacitor and resistor value below?

C83 from 0.1uF to 0.01uF;

R252 & R254 from 4.7Kohm to 10Kohm.

Please let us know if the issue is still there.

Have a great day,
Ma Hui

Re: LCP1778 I2C timing question

amandalin — Mon, 17 Apr 2017 08:39:11 GMT

Ok,i will contact RD,pls he change C82 cap to 0.01uF,if have conclusion ,i will tell you

thanks

Re: LCP1778 I2C timing question

amandalin — Thu, 27 Apr 2017 05:42:39 GMT

Dear Ma hui:

customer change C83 from 0.1uF to 0.01uF,and R252 &R254 from 4.7K to 10K,still no help

do you have others solution?

thanks

Re: LCP1778 I2C timing question

Hui_Ma — Thu, 27 Apr 2017 08:16:51 GMT

Hi Amanda,

Could you check customer measure above I2C signal from PCA9513 with I2C smart card device or not?

And if customer slow down the I2C baud rate, any modification with that signal?

Another question is how many PCA9513A chip with that issue?

Thank you for the help.

Have a great day,
Ma Hui

Re: LCP1778 I2C timing question

amandalin — Fri, 28 Apr 2017 07:53:46 GMT

Dear Hui Ma:

ok ,i will check question,thanks