i2c message max buffer size

RE: i2c message max buffer size

Øyvind — Fri, 09 Apr 2021 07:42:19 GMT

Gaurav Dubey, please open a new ticket with your issue. Please add what version of NCS you are using and what issues you are seeing.

Thanks!

Kind regards,
Øyvind

RE: i2c message max buffer size

Gaurav Dubey — Fri, 09 Apr 2021 07:01:57 GMT

[quote userid="103267" url="~/f/nordic-q-a/54308/i2c-message-max-buffer-size/303858#303858"]

I am trying to write the .msbl file to max32664c interfaced with nrf52840 and having the same issue.

I am unable to write 8210 bytes in one go and in chunks it throughs an error.

Have anyone resolved this issue

[/quote]

RE: i2c message max buffer size

Gaurav Dubey — Thu, 08 Apr 2021 16:44:32 GMT

I am trying to write the .msbl file to max32664c interfaced with nrf52840 and having the same issue.

I am unable to write 8210 bytes in one go and in chunks it throughs an error.

Have anyone resolved this issue.

RE: i2c message max buffer size

Balamurugan — Fri, 04 Sep 2020 06:20:35 GMT

Hi,

We are trying to interface nRF52832 with max32664C using i2c. While writing 8210 bytes, only 18 byes succeeds.

Facing same issue.

Have you resolved the issue and what is the solution?

RE: i2c message max buffer size

Øyvind — Tue, 19 Nov 2019 15:28:52 GMT

From what I see you will need to divide the data into chunks of let's say 1000 bytes. You will then need to write each chunk without a stop condition (opposite of what I first wrote), then on the last chunk, you write stop condition.

Kind regards,
Øyvind

RE: i2c message max buffer size

Varouzan — Fri, 15 Nov 2019 15:48:08 GMT

The device I am trying to interface with is max32664C. I am trying to flash the application firmware for it.

I am using zephyr\include\drivers\i2c.h.

RE: i2c message max buffer size

Øyvind — Fri, 15 Nov 2019 11:11:07 GMT

Can you please provide the name of the device you are trying to interface? Or a datasheet? How are you using the I2C? You should use commands found in: zephyr\include\drivers\i2c.h

Kind regards,
Øyvind

RE: i2c message max buffer size

Varouzan — Thu, 14 Nov 2019 14:10:59 GMT

Yes. I have to write the page+ checksum bytes at one transaction, so 8210 bytes at one go.

What functions am I supposed to use to utilize twim. those at zephyr\ext\hal\nordic\nrfx\drivers\include nrfx_twim.h? those at zephyr\drivers\i2c i2c_nrfx_twim.c (can't find .h header for those)?

Looking into nrf9160.h and NRF_TWIM_Type and its member TWIM_TXD_Type

typedef struct {
  __IOM uint32_t  PTR;                          /*!< (@ 0x00000000) Data pointer                                               */
  __IOM uint32_t  MAXCNT;                       /*!< (@ 0x00000004) Maximum number of bytes in transmit buffer                 */
  __IM  uint32_t  AMOUNT;                       /*!< (@ 0x00000008) Number of bytes transferred in the last transaction        */
  __IOM uint32_t  LIST;                         /*!< (@ 0x0000000C) EasyDMA list type                                          */
} TWIM_TXD_Type;

it looks like MAXCNT refers to TXD.MAXCNT?

So even with TWIM is it possible to send more that 8191 bytes? yes or no?

RE: i2c message max buffer size

Øyvind — Thu, 14 Nov 2019 08:57:35 GMT

The only I2C sample we have at the moment is the BH1749: Ambient Light Sensor IC used on the Thingy:91.

Is there a reason why you can't divide your write process into smaller chunks i.e. one page at a time with a stop condition after each page?

RE: i2c message max buffer size

Varouzan — Wed, 13 Nov 2019 16:13:12 GMT

So to work around that, I would have to use EasyDMA? Are there any examples of that or how to use EasyDMA or TWIM instead of "traditional" I2C using zephyr ?

RE: i2c message max buffer size

Øyvind — Wed, 13 Nov 2019 12:01:31 GMT

Hello,

[quote user=""]Is there a built in max length for i2c transactions? is that 8k bytes? Is there a way around that? [/quote]

The transmit buffer of the nRF9160 has a maximum value of 0x1FFF or 8191 bytes. Please see TWI Master Write Sequence for more information