net.h Configuration Parameters

This file contains all protocol stack configuration parameters. Every project must contain such a file in its source directory.

Link Layer Definitions

Baud Rate

#define LNK_BAUD_RATE   9600

Specifies your desired baud rate.

Note that the actual baud rate may differ. (see avr-manual) Also keep in mind that high rates may not be feasible due to crc generation, protocol processing time and other interrupts.

#define LNK_F_CLK       6000000

CPU clock frequency.

Used to calculate value of UBRR register.

Send Pin

The following definitions are used to specify which pin should be used to control the external bus driver.

#define LNK_SEND_PORT   PORTD
#define LNK_SEND_DDR    DDRD
#define LNK_SEND_PIN    PD4

Receive Buffer Size

#define LNK_BUFFER_SIZE 64

Specifies how many bytes should be reserved as input buffer. Packets larger than this value cannot be received and will be dropped.

Bus Timing

#define LNK_BETA_1      18

Idle time to signal end of packet (BETA_1). Measured in time slots.

#define LNK_BETA_2      24

Minimum bus idle time after packet (BETA_2). Measured in time slots.

#define LNK_ALPHA_TIME  0xd0    // value loaded into TCNT0
#define LNK_ALPHA_PRESC 0x02    // timer 0 prescaler, written to TCCR0

These values adjust the slot time ALPHA. Use the lowest prescaler that is possible to reach a maximum resulution. Otherwise the timing is prone to jitter and might be inconsistent between different nodes in the network which increases the possibility of collisions!

#define LNK_EXT_INT     INT0
#define LNK_EXT_ISCx1   ISC01
#define LNK_EXT_SIG     SIG_INTERRUPT0

Network Layer Definitions

#define NET_PHYSICAL_ADDR       0x55500002

Physical address of node.

Transport Layer Definitions

#define TSP_TIMEOUT     200

If a timeout is running and tsp_check_timeout() is called TSP_TIMEOUT times then a timeout occurs. Range: 0..255

#define TSP_MAX_GROUPS  128

Highest group id supported. The transport layer cannot send packets to groups that have an id greater than TSP_MAX_GROUPS. Consumes one byte of eeprom for every supported group id.

#define TSP_CACHE_SIZE  4       // transaction cache size
#define TSP_REPLY_SIZE  8       // pending packets

Various buffer sizes. They must be a power of two!

Appliction Layer Definitions

Define the following token to compile the static version of the application layer. If you want to compile for the dynamic version undefine it.

#define APP_STATIC

#define APP_BUFFER_SIZE 64

Size of outgoing network buffer. Packets greater than this cannot be sent.

#define APP_MAX_ASSOC   32

Number of entries in the association table. Consumes three bytes per entry.

#define APP_OBJECTS OBJECT(switch1, 2) OBJECT(switch2, 2)

Used to register application objects if compiling for the static version, otherwise it has no meaning. In the above example two objects are registered names "switch1" and "switch2" wich both have two events.

#define APP_MAX_EVENTS  8

Number of maximum pending events. MUST be a power of two!

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