Hi,
I want to use tne NRFX SPIM module for reading and writing an external spi flash (at25df011) .
I looked at the example in order to reuse it or base my application on it.
In the spi buffer parameter declaration, i find "
<Code>
#define TEST_STRING "Nordic123456789012345678901234567890"
static uint8_t m_tx_buf[] = TEST_STRING; /**< TX buffer. */
static uint8_t m_rx_buf[sizeof(TEST_STRING) + 1]; /**< RX buffer. */
static const uint8_t m_length = sizeof(m_tx_buf); /**< Transfer length. */
</Code>
and in the transfer descriptor,
<Code>
nrfx_spim_xfer_desc_t xfer_desc = NRFX_SPIM_XFER_TRX(m_tx_buf, m_length, m_rx_buf, m_length);
</Code>
However, i am wondering why the parameter m_length is declared so - "const uint8_t"
Here the test string is predefined and hence the length does not change. But in a real program, where I have to send variable number of
data bytes to the flash, this is causing a problem. I am not allowed to set the length to the required value.
The SPI driver only requires the Tx buffer to be a constant pointer, the length is not treated as constant below in the driver...
If try to make it variable - removing the "const" in the declaration, it does not compile, reporting error that the identifier needs to be a constant.
I found a workaround where a pointer is used to modify the value of length and it compiles with a warning.
Is there a better way to resolve this?
Regards
Chary BS
