Need SPI documentation

[ghost]

I'm trying to code up an spi-read function. I guess it needs to be implemented using the spi-send function but there is no documentation on how the function works. Also I would like to know how to set the spi speed correctly for the spi-init function.

If you can either provide me with an spi-read function or point me at some documentation so I can code one myself I would appreciate it.

[zeroflag]

The spi functions are based on the spi.c from esp-open-rtos.

There is a thin wrapper:

https://github.com/zeroflag/punyforth/blob/feab7a0fea1c815a5dc441085251fdea44c7089e/arch/esp8266/rtos/user/forth_spi.c

And the Forth words are here:

https://github.com/zeroflag/punyforth/blob/6a2e89c1969c12798d627f9b5c49326139f99e8a/arch/esp8266/ext.S#L394

There isn't any user friendly documentation yet, but you can check the stack usage.

For example spi-send8 is defined as follows:

defprimitive "spi-send8",9,spi_send8,REGULAR
    DPOP a2                    // bus
    DPOP a3                    // data
    CCALL forth_spi_send8
    DPUSH a2
    NEXT

So the stack effect should be

: spi-send8 ( data bus -- result )

I think you're right saying that the read should be implemented by using the send. But I didn't need to use read so far.

There are some examples of using spi-init and send in

https://github.com/zeroflag/punyforth/blob/master/arch/esp8266/forth/ssd1306-spi.forth

[ghost]

Hi Attila

Yes I've investigated all of that over the last couple of days but it doesn't explain how to use spi-send for example. There is an indata and an outdata pointer but in reference to what? Is indata the data read from the spi interface or the data being sent out of the interface? Also, does one have to pass 0xFF into the function for each byte that is being read?

The low level functions that the forth words call must be documented somewhere.

Also in the spi-init function has a freq-div parameter. It it set using your function

5 2 spi-get-freq-div constant: SPI_FREQ_DIV_8M

does this constant divide the ESP8266 clock by 8 million or does it provide an 8 Meg clock for spi?

If you get a chance to write an spi-read function I would love to see it.

BTW, I'm trying to use Punyforth to build an Internet radio. I will give you this code if and when I get it working.

Craig Lindley

On Mon, Sep 11, 2017 at 10:20 AM, Attila Magyar notifications@github.com wrote:

The spi functions are based on

There is a thin wrapper:

https://github.com/zeroflag/punyforth/blob/feab7a0fea1c815a5dc441085251fd ea44c7089e/arch/esp8266/rtos/user/forth_spi.c

And the Forth words are here:

https://github.com/zeroflag/punyforth/blob/6a2e89c1969c12798d627f9b5c4932 6139f99e8a/arch/esp8266/ext.S#L394

There isn't any user friendly documentation yet, but you can check the stack usage.

For example spi-send8 is defined as follows:

defprimitive "spi-send8",9,spi_send8,REGULAR DPOP a2 // bus DPOP a3 // data CCALL forth_spi_send8 DPUSH a2 NEXT

So the stack effect should be

: spi-send8 ( data bus -- result )

I think you're right saying that the read should be implemented by using the send. But I didn't need to use read so far.

There are some examples of using spi-init and send in

https://github.com/zeroflag/punyforth/blob/master/arch/ esp8266/forth/ssd1306-spi.forth

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub https://github.com/zeroflag/punyforth/issues/31#issuecomment-328581396, or mute the thread https://github.com/notifications/unsubscribe-auth/AEM6-LZo3e2p0hAsTE_lclwjO0D2HCvpks5shV21gaJpZM4PTZiI .

-- Craig Lindley / Heather Hubbard

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Personal Website: craigandheather.net

Phone: (719) 495-1873 Cell: (719) 502-7925

If you’re one in a million, there are now seven thousand people exactly like you.

[zeroflag]

Here is the documentation of spi_transfer from https://github.com/SuperHouse/esp-open-rtos/blob/61c3d509e5b930c6c1b269ceff99e2d1f60d2010/core/include/esp/spi.h#L275

 * \param bus Bus ID: 0 - system, 1 - user
 * \param out_data Data to send.
 * \param in_data Receive buffer. If NULL, received data will be lost.
 * \param len Buffer size in words
 * \param word_size Size of the word
 * \return Transmitted/received words count
 */
size_t spi_transfer(uint8_t bus, const void *out_data, void *in_data, size_t len, spi_word_size_t word_size);

So the out_data buffer contains the data to be sent and the other one is the receive buffer. I didn't need the receive buffer when I used this (I just passed 0) so I don't have more information on this beside what's in the C comment.

This may help regarding the spi-get-freq-div constant.

/**
 * Macro for use with spi_init and spi_set_frequency_div.
 * SPI frequency = 80000000 / divider / count
 * dvider must be in 1..8192 and count in 1..64
 */
#define SPI_GET_FREQ_DIV(divider, count) (((count) << 16) | ((divider) & 0xffff))

/**
 * Predefinded SPI frequency dividers
 */
#define SPI_FREQ_DIV_125K SPI_GET_FREQ_DIV(64, 10) ///< 125kHz
#define SPI_FREQ_DIV_250K SPI_GET_FREQ_DIV(32, 10) ///< 250kHz
#define SPI_FREQ_DIV_500K SPI_GET_FREQ_DIV(16, 10) ///< 500kHz
#define SPI_FREQ_DIV_1M   SPI_GET_FREQ_DIV(8, 10)  ///< 1MHz
#define SPI_FREQ_DIV_2M   SPI_GET_FREQ_DIV(4, 10)  ///< 2MHz
#define SPI_FREQ_DIV_4M   SPI_GET_FREQ_DIV(2, 10)  ///< 4MHz
#define SPI_FREQ_DIV_8M   SPI_GET_FREQ_DIV(5,  2)  ///< 8MHz
#define SPI_FREQ_DIV_10M  SPI_GET_FREQ_DIV(4,  2)  ///< 10MHz
#define SPI_FREQ_DIV_20M  SPI_GET_FREQ_DIV(2,  2)  ///< 20MHz
#define SPI_FREQ_DIV_40M  SPI_GET_FREQ_DIV(1,  2)  ///< 40MHz
#define SPI_FREQ_DIV_80M  SPI_GET_FREQ_DIV(1,  1)  ///< 80MHz

[ghost]

Thanks this helps. I'll try to write my spi-read8 function using this information.

On Mon, Sep 11, 2017 at 11:17 AM, Attila Magyar notifications@github.com wrote:

Here is the documentation of spi_transfer from https://github.com/SuperHouse/esp-open-rtos/blob/ 61c3d509e5b930c6c1b269ceff99e2d1f60d2010/core/include/esp/spi.h#L275

• \param bus Bus ID: 0 - system, 1 - user
• \param out_data Data to send.
• \param in_data Receive buffer. If NULL, received data will be lost.
• \param len Buffer size in words
• \param word_size Size of the word
• \return Transmitted/received words count / size_t spi_transfer(uint8_t bus, const void out_data, void *in_data, size_t len, spi_word_size_t word_size);

So the out_data buffer contains the data to be sent and the other one is the receive buffer. I didn't need the receive buffer when I used this (I just passed 0) so I don't have more information on this beside what's in the C comment.

This may help regarding the spi-get-freq-div constant.

/**

• Macro for use with spi_init and spi_set_frequency_div.
• SPI frequency = 80000000 / divider / count
• dvider must be in 1..8192 and count in 1..64 */

  define SPI_GET_FREQ_DIV(divider, count) (((count) << 16) | ((divider) & 0xffff))

/**

• Predefinded SPI frequency dividers */

  define SPI_FREQ_DIV_125K SPI_GET_FREQ_DIV(64, 10) ///< 125kHz

  define SPI_FREQ_DIV_250K SPI_GET_FREQ_DIV(32, 10) ///< 250kHz

  define SPI_FREQ_DIV_500K SPI_GET_FREQ_DIV(16, 10) ///< 500kHz

  define SPI_FREQ_DIV_1M SPI_GET_FREQ_DIV(8, 10) ///< 1MHz

  define SPI_FREQ_DIV_2M SPI_GET_FREQ_DIV(4, 10) ///< 2MHz

  define SPI_FREQ_DIV_4M SPI_GET_FREQ_DIV(2, 10) ///< 4MHz

  define SPI_FREQ_DIV_8M SPI_GET_FREQ_DIV(5, 2) ///< 8MHz

  define SPI_FREQ_DIV_10M SPI_GET_FREQ_DIV(4, 2) ///< 10MHz

  define SPI_FREQ_DIV_20M SPI_GET_FREQ_DIV(2, 2) ///< 20MHz

  define SPI_FREQ_DIV_40M SPI_GET_FREQ_DIV(1, 2) ///< 40MHz

  define SPI_FREQ_DIV_80M SPI_GET_FREQ_DIV(1, 1) ///< 80MHz

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-- Craig Lindley / Heather Hubbard

495's Recordings: craigandheather.net/495spage.html New Recordings: craigandheather.net/cnmpage.html Latest rock CD: craigandheather.net/oneinarow.html Latest non-rock CD: craigandheather.net/craigdoesfingerstyle.html

Personal Website: craigandheather.net

Phone: (719) 495-1873 Cell: (719) 502-7925

If you’re one in a million, there are now seven thousand people exactly like you.