The second function is the device driver Start()
function. This function is called once each time an interface is started.
Files
Every device driver’s net_dev.c
Prototype
Note that since every device driver’s Start()
function is accessed only by function pointer via the device driver’s API structure, it doesn’t need to be globally available and should therefore be declared as ‘static
’.
Arguments
pif
Pointer to the interface to start a network device.
perr
Pointer to variable that will receive the return error code from this function.
Returned Value
None.
Required Configuration
None.
Notes / Warnings
The Start()
function performs the following items:
NetOS_Dev_CfgTxRdySignal()
. This function call is optional and is generally performed when the hardware device supports the queuing of multiple transmit frames. By default, the count is initialized to one. However, DMA devices should set the semaphore count equal to the number of configured transmit descriptors for optimal performance. Non-DMA devices that support the queuing of more than one transmit frame may also benefit from a non-default value.a. Configure the MAC address using the string found within the device configuration structure. This is a form of static MAC address configuration and may be performed by calling NetASCII_Str_to_MAC()
and NetIF_AddrHW_SetHandler()
. If the device configuration string has been left empty, or is specified as all 0’s, an error will be returned and the next method should be attempted.
b. Check if the application developer has called NetIF_AddrHW_Set()
by making a call to NetIF_AddrHW_GetHandler()
and NetIF_AddrHW_IsValidHandler()
in order to check if the specified MAC address is valid. This method may be used as a static method for configuring the MAC address during run-time, or a dynamic method should a pre-programmed external memory device exist. If the acquired MAC address does not pass the check function, then:
c. Call NetIF_AddrHW_SetHandler()
using the data found within the MAC individual address registers. If an auto-loading EEPROM is attached to the MAC, the registers will contain valid data. If not, then a configuration error has occurred. This method is often used with a production process where the MAC supports the automatic loading of individual address registers from a serial EEPROM. When using this method, the developer should specify an empty string for the MAC address within the device configuration and refrain from calling NetIF_AddrHW_Set()
from within the application.
Init()
function.perr
equal to NET_DEV_ERR_NONE
if no errors have occurred. Otherwise, set perr
to an appropriate network device error code.