Configuration of MAX7301

Configuration of MAX7301

[Vikram Narayanan]

Hi,

I am trying to interface the MAX7301 IC with my Samsung S3C2440 processor.
The problem is the S3c supports only 8 bit word length for SPI transfer,
whereas my MAX requires 16 bit word length.
I couldn't find any info on the datasheet to use the IC on a 8 bit word
length. can i make the max7301_write function,

static int max7301_write(struct spi_device *spi, unsigned int reg, unsigned
int val)
{
    u8 command = reg & 0x7F;
    u8 data = val & 0xFF;
    spi_write(spi, (const u8*)&command, sizeof(command));
    spi_write(spi, (const u8*)&data, sizeof(data));
    return 0;
}

Will this make the IC work? Please share your ideas.
--
Regards
Vikram
------------------------------------------------------------------------------
Free Software Download: Index, Search & Analyze Logs and other IT data in 
Real-Time with Splunk. Collect, index and harness all the fast moving IT data 
generated by your applications, servers and devices whether physical, virtual
or in the cloud. Deliver compliance at lower cost and gain new business 
insights. http://p.sf.net/sfu/splunk-dev2dev 

Re: Configuration of MAX7301

[Jassi Brar]

On Thu, Mar 3, 2011 at 2:57 AM, Vikram Narayanan <vikram186@gmail.com> wrote:
> Hi,
>
> I am trying to interface the MAX7301 IC with my Samsung S3C2440 processor.
> The problem is the S3c supports only 8 bit word length for SPI transfer,
> whereas my MAX requires 16 bit word length.
> I couldn't find any info on the datasheet to use the IC on a 8 bit word
> length. can i make the max7301_write function,
>
> static int max7301_write(struct spi_device *spi, unsigned int reg, unsigned
> int val)
> {
>    u8 command = reg & 0x7F;
>    u8 data = val & 0xFF;
>    spi_write(spi, (const u8*)&command, sizeof(command));
>    spi_write(spi, (const u8*)&data, sizeof(data));
>    return 0;
> }
>
> Will this make the IC work? Please share your ideas.

If MAX7301 does require exactly 16bpw, typecasting wouldn't do.

For simple control purposes, one option is to use the SPI pins with
the common bit-banging driver.

> --
> Regards
> Vikram
> ------------------------------------------------------------------------------
> Free Software Download: Index, Search & Analyze Logs and other IT data in
> Real-Time with Splunk. Collect, index and harness all the fast moving IT data
> generated by your applications, servers and devices whether physical, virtual
> or in the cloud. Deliver compliance at lower cost and gain new business
> insights. http://p.sf.net/sfu/splunk-dev2dev
> _______________________________________________
> spi-devel-general mailing list
> spi-devel-general@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/spi-devel-general
>

------------------------------------------------------------------------------
Free Software Download: Index, Search & Analyze Logs and other IT data in 
Real-Time with Splunk. Collect, index and harness all the fast moving IT data 
generated by your applications, servers and devices whether physical, virtual
or in the cloud. Deliver compliance at lower cost and gain new business 
insights. http://p.sf.net/sfu/splunk-dev2dev 
_______________________________________________
spi-devel-general mailing list
spi-devel-general@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/spi-devel-general

Re: Configuration of MAX7301

[Vikram Narayanan]

Thanks for the hint.
I tried using the MAX7301 with the bi banging driver. But it doesn't seem to
get initialized.
The Init code of max7301.c says this.
static int __init max7301_init(void)
{
    return spi_register_driver(&max7301_driver);
}
/* register after spi postcore initcall and before
 * subsys initcalls that may rely on these GPIOs
 */
subsys_initcall(max7301_init);

1) Is it ok to call the spi_regiser_driver even when I use the bitbanging
driver? I don't get any error or prints when I insert the module. I guess
the spi_register_driver is not at all executed. If it is executed then it
would have called the probe function. //Correct me if I am wrong.

2) Is the line subsys_initcall really needed as my driver is going to get
itself registered with the bit banging driver?

On Thu, Mar 3, 2011 at 6:07 AM, Jassi Brar <jassisinghbrar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:

> On Thu, Mar 3, 2011 at 2:57 AM, Vikram Narayanan <vikram186-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> wrote:
> > Hi,
> >
> > I am trying to interface the MAX7301 IC with my Samsung S3C2440
> processor.
> > The problem is the S3c supports only 8 bit word length for SPI transfer,
> > whereas my MAX requires 16 bit word length.
> > I couldn't find any info on the datasheet to use the IC on a 8 bit word
> > length. can i make the max7301_write function,
> >
> > static int max7301_write(struct spi_device *spi, unsigned int reg,
> unsigned
> > int val)
> > {
> >    u8 command = reg & 0x7F;
> >    u8 data = val & 0xFF;
> >    spi_write(spi, (const u8*)&command, sizeof(command));
> >    spi_write(spi, (const u8*)&data, sizeof(data));
> >    return 0;
> > }
> >
> > Will this make the IC work? Please share your ideas.
>
> If MAX7301 does require exactly 16bpw, typecasting wouldn't do.
>
> For simple control purposes, one option is to use the SPI pins with
> the common bit-banging driver.
>
> > --
> > Regards
> > Vikram
> >
> ------------------------------------------------------------------------------
> > Free Software Download: Index, Search & Analyze Logs and other IT data in
> > Real-Time with Splunk. Collect, index and harness all the fast moving IT
> data
> > generated by your applications, servers and devices whether physical,
> virtual
> > or in the cloud. Deliver compliance at lower cost and gain new business
> > insights. http://p.sf.net/sfu/splunk-dev2dev
> > _______________________________________________
> > spi-devel-general mailing list
> > spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
> > https://lists.sourceforge.net/lists/listinfo/spi-devel-general
> >
>
------------------------------------------------------------------------------
Free Software Download: Index, Search & Analyze Logs and other IT data in 
Real-Time with Splunk. Collect, index and harness all the fast moving IT data 
generated by your applications, servers and devices whether physical, virtual
or in the cloud. Deliver compliance at lower cost and gain new business 
insights. http://p.sf.net/sfu/splunk-dev2dev 

Re: Configuration of MAX7301

[Vikram Narayanan]

These are the changes I have done in my board file to make the max7301 work
with S3C24xx spi driver.

static struct s3c2410_spi_info mini2440_spi0_platdata = {
    .pin_cs = S3C2410_GPG(2),
    .num_cs = 1,
    .bus_num = 0,
};

static struct max7301_platform_data max7301_info = {
    .base = -1,
};
// The base is set as -1 since from max7301.c there is a call to
gpiochip_add, which would return if there is no base set.
>From the comment in the drivers/gpio/gpiolib.c

 <http://lxr.linux.no/linux+*/drivers/gpio/gpiolib.c#L912>If
chip->base is negative, this requests dynamic assignment of
<http://lxr.linux.no/linux+*/drivers/gpio/gpiolib.c#L913>a range of
valid GPIOs.

static struct spi_board_info mini2440_spi_board_info[] __initdata = {
    {
        .modalias    = "max7301",
        .platform_data    = &max7301_info,
        .max_speed_hz    = 13000000,
        .bus_num    = 0,
        .chip_select    = 0,
        .mode        = SPI_MODE_0,
    },
};

And from board init I am configuring the pins for SPI

    s3c2410_gpio_cfgpin(S3C2410_GPE(11), S3C2410_GPE11_SPIMISO0);
    s3c2410_gpio_cfgpin(S3C2410_GPE(12), S3C2410_GPE12_SPIMOSI0);
    s3c2410_gpio_cfgpin(S3C2410_GPE(13), S3C2410_GPE13_SPICLK0);
    s3c2410_gpio_pullup(S3C2410_GPE(11), 0);
    s3c2410_gpio_pullup(S3C2410_GPE(13), 0);
    s3c2410_gpio_cfgpin(S3C2410_GPG(2), S3C2410_GPIO_OUTPUT);
    s3c_device_spi0.dev.platform_data = &mini2440_spi0_platdata;
    spi_register_board_info(mini2440_spi_board_info,
        ARRAY_SIZE(mini2440_spi_board_info));

And in the max7301.c I have changed the
spi->bits_per_word = 8;

as my SPI master driver would not initialize the value isn't equal to 8.

When I insert the max7301 module now, I am getting error which traces back
to the file drivers/gpio/gpiolib.c

    if (status)
        pr_err("gpiochip_add: gpios %d..%d (%s) not registered\n",
            chip->base, chip->base + chip->ngpio - 1,
            chip->label ? : "generic");

gpiochip add: gpios -1...26 (max7301) not registered.

I don't get a clear picture of what is wrong with the SPI configuration I
have done.
Can someone help me understanding what is wrong?

On Thu, Mar 3, 2011 at 4:37 PM, Jassi Brar <jassisinghbrar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:

> On Thu, Mar 3, 2011 at 2:57 AM, Vikram Narayanan <vikram186-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> wrote:
> > Hi,
> >
> > I am trying to interface the MAX7301 IC with my Samsung S3C2440
> processor.
> > The problem is the S3c supports only 8 bit word length for SPI transfer,
> > whereas my MAX requires 16 bit word length.
> > I couldn't find any info on the datasheet to use the IC on a 8 bit word
> > length. can i make the max7301_write function,
> >
> > static int max7301_write(struct spi_device *spi, unsigned int reg,
> unsigned
> > int val)
> > {
> >    u8 command = reg & 0x7F;
> >    u8 data = val & 0xFF;
> >    spi_write(spi, (const u8*)&command, sizeof(command));
> >    spi_write(spi, (const u8*)&data, sizeof(data));
> >    return 0;
> > }
> >
> > Will this make the IC work? Please share your ideas.
>
> If MAX7301 does require exactly 16bpw, typecasting wouldn't do.
>
> For simple control purposes, one option is to use the SPI pins with
> the common bit-banging driver.
>
> > --
> > Regards
> > Vikram
> >
> ------------------------------------------------------------------------------
> > Free Software Download: Index, Search & Analyze Logs and other IT data in
> > Real-Time with Splunk. Collect, index and harness all the fast moving IT
> data
> > generated by your applications, servers and devices whether physical,
> virtual
> > or in the cloud. Deliver compliance at lower cost and gain new business
> > insights. http://p.sf.net/sfu/splunk-dev2dev
> > _______________________________________________
> > spi-devel-general mailing list
> > spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
> > https://lists.sourceforge.net/lists/listinfo/spi-devel-general
> >
>
------------------------------------------------------------------------------
Free Software Download: Index, Search & Analyze Logs and other IT data in 
Real-Time with Splunk. Collect, index and harness all the fast moving IT data 
generated by your applications, servers and devices whether physical, virtual
or in the cloud. Deliver compliance at lower cost and gain new business 
insights. http://p.sf.net/sfu/splunk-dev2dev 

Re: Configuration of MAX7301

[Grant Likely]

On Thu, Mar 3, 2011 at 3:57 AM, Vikram Narayanan <vikram186-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> Hi,
>
> I am trying to interface the MAX7301 IC with my Samsung S3C2440 processor.
> The problem is the S3c supports only 8 bit word length for SPI transfer,
> whereas my MAX requires 16 bit word length.

You're talking about spi which at it's heart is just a stream of bits.
 Not 8 bit, not 16 bit.  Just a stream.  The device may make
assumptions about how the stream is framed into 16 bit hunks, and the
spi_master may have limitations on how the data buffer is organized (8
bit bytes), but that does not prevent the two from working together.

What you need to do is arrange the data in the transfer buffer so that
the bits get streamed out in the order expected by the MAX7301.  It's
educational to break out an oscilloscope and experiment with different
transfers so you can get familiar with how the bits appear on the
wire.  Then you'll be able to figure out how to arrange the transfer
so that the device gets what it needs.

I do *not* recommend using the bitbang driver when you've got a proper
spi master at your disposal.

g.

> I couldn't find any info on the datasheet to use the IC on a 8 bit word
> length. can i make the max7301_write function,
>
> static int max7301_write(struct spi_device *spi, unsigned int reg, unsigned
> int val)
> {
>    u8 command = reg & 0x7F;
>    u8 data = val & 0xFF;
>    spi_write(spi, (const u8*)&command, sizeof(command));
>    spi_write(spi, (const u8*)&data, sizeof(data));
>    return 0;
> }
>
> Will this make the IC work? Please share your ideas.
> --
> Regards
> Vikram
> ------------------------------------------------------------------------------
> Free Software Download: Index, Search & Analyze Logs and other IT data in
> Real-Time with Splunk. Collect, index and harness all the fast moving IT data
> generated by your applications, servers and devices whether physical, virtual
> or in the cloud. Deliver compliance at lower cost and gain new business
> insights. http://p.sf.net/sfu/splunk-dev2dev
> _______________________________________________
> spi-devel-general mailing list
> spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
> https://lists.sourceforge.net/lists/listinfo/spi-devel-general
>



-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.

------------------------------------------------------------------------------
Free Software Download: Index, Search & Analyze Logs and other IT data in 
Real-Time with Splunk. Collect, index and harness all the fast moving IT data 
generated by your applications, servers and devices whether physical, virtual
or in the cloud. Deliver compliance at lower cost and gain new business 
insights. http://p.sf.net/sfu/splunk-dev2dev 

Re: Configuration of MAX7301

[Vikram Narayanan]

 I agree with you. Even in an example for MAX7301 with 8051 controller, they
are sending the first 8 bits followed by the next 8 bits. I am now clear
with the idea that this can be achieved this way. Thanks for your
suggestions.
I did some changes and the driver loads fine now. I want to know whether the
clock should be enabled by me or it ll be enabled when the pins are
configured as SPI pins.

On Thu, Mar 3, 2011 at 10:27 PM, Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>wrote:

> On Thu, Mar 3, 2011 at 3:57 AM, Vikram Narayanan <vikram186-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> wrote:
> > Hi,
> >
> > I am trying to interface the MAX7301 IC with my Samsung S3C2440
> processor.
> > The problem is the S3c supports only 8 bit word length for SPI transfer,
> > whereas my MAX requires 16 bit word length.
>
> You're talking about spi which at it's heart is just a stream of bits.
>  Not 8 bit, not 16 bit.  Just a stream.  The device may make
> assumptions about how the stream is framed into 16 bit hunks, and the
> spi_master may have limitations on how the data buffer is organized (8
> bit bytes), but that does not prevent the two from working together.
>
> What you need to do is arrange the data in the transfer buffer so that
> the bits get streamed out in the order expected by the MAX7301.  It's
> educational to break out an oscilloscope and experiment with different
> transfers so you can get familiar with how the bits appear on the
> wire.  Then you'll be able to figure out how to arrange the transfer
> so that the device gets what it needs.
>
> I do *not* recommend using the bitbang driver when you've got a proper
> spi master at your disposal.
>
> g.
>
> > I couldn't find any info on the datasheet to use the IC on a 8 bit word
> > length. can i make the max7301_write function,
> >
> > static int max7301_write(struct spi_device *spi, unsigned int reg,
> unsigned
> > int val)
> > {
> >    u8 command = reg & 0x7F;
> >    u8 data = val & 0xFF;
> >    spi_write(spi, (const u8*)&command, sizeof(command));
> >    spi_write(spi, (const u8*)&data, sizeof(data));
> >    return 0;
> > }
> >
> > Will this make the IC work? Please share your ideas.
> > --
> > Regards
> > Vikram
> >
> ------------------------------------------------------------------------------
> > Free Software Download: Index, Search & Analyze Logs and other IT data in
> > Real-Time with Splunk. Collect, index and harness all the fast moving IT
> data
> > generated by your applications, servers and devices whether physical,
> virtual
> > or in the cloud. Deliver compliance at lower cost and gain new business
> > insights. http://p.sf.net/sfu/splunk-dev2dev
> > _______________________________________________
> > spi-devel-general mailing list
> > spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
> > https://lists.sourceforge.net/lists/listinfo/spi-devel-general
> >
>
>
>
> --
> Grant Likely, B.Sc., P.Eng.
> Secret Lab Technologies Ltd.
>
------------------------------------------------------------------------------
Free Software Download: Index, Search & Analyze Logs and other IT data in 
Real-Time with Splunk. Collect, index and harness all the fast moving IT data 
generated by your applications, servers and devices whether physical, virtual
or in the cloud. Deliver compliance at lower cost and gain new business 
insights. http://p.sf.net/sfu/splunk-dev2dev 

Re: Configuration of MAX7301

[Vikram Narayanan]

I have made changes in the BSP such that the SPI works fine. Now I made
changes in max7301.c

1. changed the bits/word to 8

2. called spi_write twice to transfer the 16 bits (yet to check with a DSO
to ensure that this method works fine)

3. commented the gpiochip_add call.
Reason:
The error when I call this from my probe function is
gpiochip_add: gpios -1..26 (max7301) not registered
max7301: probe of spi0.0 failed with error -28

Finally, the MAX7301 doesn't seem to work :(


On Thu, Mar 3, 2011 at 10:38 PM, Vikram Narayanan <vikram186-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>wrote:

> I agree with you. Even in an example for MAX7301 with 8051 controller, they
> are sending the first 8 bits followed by the next 8 bits. I am now clear
> with the idea that this can be achieved this way. Thanks for your
> suggestions.
> I did some changes and the driver loads fine now. I want to know whether
> the clock should be enabled by me or it ll be enabled when the pins are
> configured as SPI pins.
>
>
> On Thu, Mar 3, 2011 at 10:27 PM, Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>wrote:
>
>> On Thu, Mar 3, 2011 at 3:57 AM, Vikram Narayanan <vikram186-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> wrote:
>> > Hi,
>> >
>> > I am trying to interface the MAX7301 IC with my Samsung S3C2440
>> processor.
>> > The problem is the S3c supports only 8 bit word length for SPI transfer,
>> > whereas my MAX requires 16 bit word length.
>>
>> You're talking about spi which at it's heart is just a stream of bits.
>>  Not 8 bit, not 16 bit.  Just a stream.  The device may make
>> assumptions about how the stream is framed into 16 bit hunks, and the
>> spi_master may have limitations on how the data buffer is organized (8
>> bit bytes), but that does not prevent the two from working together.
>>
>> What you need to do is arrange the data in the transfer buffer so that
>> the bits get streamed out in the order expected by the MAX7301.  It's
>> educational to break out an oscilloscope and experiment with different
>> transfers so you can get familiar with how the bits appear on the
>> wire.  Then you'll be able to figure out how to arrange the transfer
>> so that the device gets what it needs.
>>
>> I do *not* recommend using the bitbang driver when you've got a proper
>> spi master at your disposal.
>>
>> g.
>>
>> > I couldn't find any info on the datasheet to use the IC on a 8 bit word
>> > length. can i make the max7301_write function,
>> >
>> > static int max7301_write(struct spi_device *spi, unsigned int reg,
>> unsigned
>> > int val)
>> > {
>> >    u8 command = reg & 0x7F;
>> >    u8 data = val & 0xFF;
>> >    spi_write(spi, (const u8*)&command, sizeof(command));
>> >    spi_write(spi, (const u8*)&data, sizeof(data));
>> >    return 0;
>> > }
>> >
>> > Will this make the IC work? Please share your ideas.
>> > --
>> > Regards
>> > Vikram
>> >
>> ------------------------------------------------------------------------------
>> > Free Software Download: Index, Search & Analyze Logs and other IT data
>> in
>> > Real-Time with Splunk. Collect, index and harness all the fast moving IT
>> data
>> > generated by your applications, servers and devices whether physical,
>> virtual
>> > or in the cloud. Deliver compliance at lower cost and gain new business
>> > insights. http://p.sf.net/sfu/splunk-dev2dev
>> > _______________________________________________
>> > spi-devel-general mailing list
>> > spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
>> > https://lists.sourceforge.net/lists/listinfo/spi-devel-general
>> >
>>
>>
>>
>> --
>> Grant Likely, B.Sc., P.Eng.
>> Secret Lab Technologies Ltd.
>>
>
>
------------------------------------------------------------------------------
Free Software Download: Index, Search & Analyze Logs and other IT data in 
Real-Time with Splunk. Collect, index and harness all the fast moving IT data 
generated by your applications, servers and devices whether physical, virtual
or in the cloud. Deliver compliance at lower cost and gain new business 
insights. http://p.sf.net/sfu/splunk-dev2dev