NRF minimal radio driver

Minimal driver for the NRF51 radio. More...

Detailed Description

Minimal driver for the NRF51 radio.

This driver uses the nRF5x radio in a proprietary/custom way, defining our own custom link layer. This custom link layer resembles some characteristics of the IEEE802.15.4 link layer, but is not at all compatible to it.

One key point is, that this custom link layer is only meant to operate between nRF5x devices, which let's us make some very nice assumptions:

• all communicating hosts are little-endian -> we define host byte order := network byte order

The driver is using a Nordic proprietary physical layer, configured to a bitrate of 1 Mbit/s. The maximum payload length can be freely configured, but the maximal supported value is 250 byte (default is 200 byte).

We define the nrfmin link layer to use 16-bit addresses. On the physical layer we encode these addresses by putting these addresses into the 2 least significant bytes of the supported 5-byte addresses, while setting the other 3 bytes to 0xe7.

For out custom link layer, we define our own proprietary link layer format (all fields are in host byte order (little endian)):

byte0	byte1 - byte2	byte3 - byte4	byte5	byte7 - byteN
length	src_addr	dst_addr	proto	payload...

With:

• length: length of the packet, including the header -> payload len + 6
• src_addr: 16-bit source address
• dst_addr: 16-bit destination address
• proto: type of data transferred (similar to an Ethertype field)

SUMMARY: This driver / link layer supports:

• 16-bit addressing (16-bit) -> extract default address from CPU ID
• broadcast (broadcast address is ff:ff)
• channels from 0 to 31 [2400MHz to 2524MHz, 4MHz per channel]
• setting of TX power [+4dBm to -20dBm, in ~4dBm steps]
• 8-bit packet type/proto field (to be used as seen fit)
• setting device state (RX, SLEEP)

But so far no support for:

• link layer ACKs
• retransmissions

Todo:

So far the driver uses only a single RX buffer that is locked until the data was read/discarded. This can potentially lead to a lot of packet loss -> using more than one buffer would help here...

Modules
	GNRC adapter for nrfmin
	Minimal driver for the NRF51 radio.

Files
file	nrfmin.h
	Interface definition for the nrfmin NRF51822 radio driver.

Data Structures
struct	nrfmin_hdr_t
	Header format used for our custom nrfmin link layer. More...
union	nrfmin_pkt_t
	In-memory structure of a nrfmin radio packet. More...

Macros
#define	NRFMIN_TXPOWER_DEFAULT   (0) /* 0dBm */
	Default transmission power used.
#define	NRFMIN_ADDR_BCAST   (0xffff)
	Export the default nrfmin broadcast address.
#define	NRFMIN_PAYLOAD_MAX   (200U)
	Default maximum payload length (must be <= 250)

Functions
void	nrfmin_setup (void)
	Setup the device driver's data structures.
uint16_t	nrfmin_get_addr (void)
	Get the currently active address. More...
void	nrfmin_set_addr (uint16_t addr)
	Set the 16-bit radio address. More...
void	nrfmin_get_iid (uint16_t *iid)
	Get the IID build from the 16-bit node address. More...
uint16_t	nrfmin_get_channel (void)
	Get the current channel. More...
int	nrfmin_set_channel (uint16_t chan)
	Set the active channel. More...
netopt_state_t	nrfmin_get_state (void)
	Get the current radio state. More...
int	nrfmin_set_state (netopt_state_t val)
	Put the device into the given state. More...
int16_t	nrfmin_get_txpower (void)
	Get the current transmit power. More...
void	nrfmin_set_txpower (int16_t power)
	Set the used transmission power. More...

Variables
netdev_t	nrfmin_dev
	Export the netdev device descriptor.
const netdev_driver_t	nrfmin_netdev
	Reference to the netdev driver interface.
#define	NRFMIN_CHAN_MIN   (0U)
	nrfmin channel configuration
#define	NRFMIN_CHAN_DEFAULT   (0U) /* 2400MHz */
#define	NRFMIN_CHAN_MAX   (32)
#define	NRFMIN_HDR_LEN   (sizeof(nrfmin_hdr_t))
	Export some information on header and packet lengths.
#define	NRFMIN_PKT_MAX   (NRFMIN_HDR_LEN + NRFMIN_PAYLOAD_MAX)

Function Documentation

nrfmin_get_addr()

uint16_t nrfmin_get_addr

(

void

)

Get the currently active address.

Returns

the 16-bit node address

nrfmin_get_channel()

uint16_t nrfmin_get_channel

(

void

)

Get the current channel.

Returns

currently active channel

nrfmin_get_iid()

void nrfmin_get_iid

(

uint16_t *

iid

)

Get the IID build from the 16-bit node address.

Parameters

[out]

iid

the 64-bit IID, as array of 4 * 16-bit

nrfmin_get_state()

netopt_state_t nrfmin_get_state

(

void

)

Get the current radio state.

Returns

state the radio is currently in

nrfmin_get_txpower()

int16_t nrfmin_get_txpower

(

void

)

Get the current transmit power.

Returns

transmission power in [dBm]

nrfmin_set_addr()

void nrfmin_set_addr

(

uint16_t

addr

)

Set the 16-bit radio address.

Parameters

[in]

addr

address to set

nrfmin_set_channel()

int nrfmin_set_channel

(

uint16_t

chan

)

Set the active channel.

Parameters

[in]

chan

targeted channel [0-31]

Returns

sizeof(uint16_t) on success

-EOVERFLOW if channel is not applicable

nrfmin_set_state()

int nrfmin_set_state

(

netopt_state_t

val

)

Put the device into the given state.

Parameters

[in]

val

target state

Returns

sizeof(netopt_state_t) on success

-ENOTSUP if target state is not applicable

nrfmin_set_txpower()

void nrfmin_set_txpower

(

int16_t

power

)

Set the used transmission power.

Parameters

[in]

power

targeted power, in [dBm]