Echelon Neuron C - Manual (Page 210)

198 Memory Management
If explicit addressing is used for network variables:
C = max(34, 19 + sizeof(largest NV))
The application input buffer must be sized to accommodate incoming
responses in addition to other incoming messages.
D. receive_trans_count default
If explicit messages are received by the application program:
D = max(8, min (16, # of non-config input NVs + 2))
If explicit messages are not received by the application program:
D = min(16, # of non-config input NVs + 2)
E. app_buf_out_count, app_buf_out_priority_count, net_buf_out_count, and
net_buf_out_priority_count defaults
If the application is linked for a Neuron 3120 Chip or a Neuron 3120E1 Chip:
E = 1
If the application is linked for any other Neuron Chip or Smart Transceiver:
E = 2
When priority buffer counts are set to zero, all network variables are marked
as non-priority nonconfig. If app_buf_out_priority_count or
net_buf_out_priority_count is non-zero, then both must be non-zero, and two
transmit transaction buffers are automatically allocated in RAM. If there are
no priority output buffers, then only one transmit transaction buffer is
allocated. The size of a transmit transaction buffer is 28 bytes (in versions 4,
6, and later, of the Neuron firmware), and 18 bytes (in earlier versions).
The Neuron C compiler determines that a program uses explicit addressing if it
references any of the following:
msg_in.addr
resp_in.addr
msg_out.dest_addr
nv_in_addr
Usage Tip for Memory-Mapped I/O
You can attach memory-mapped I/O devices to a Neuron 3150 Chip or FT 3150
Smart Transceiver. You cannot use memory mapped I/O with Series 5000 chips,
but you can expand the I/O capabilities of all Neuron Chips and Smart
Transceivers by accessing a peripheral I/O device using one of the supported I/O
models, such as an SPI PIO device.
Memory-mapped devices should respond only to memory addresses that are
outside the configured memory map areas for ROM, EEPROM, and RAM.
A convenient method of access to memory-mapped I/O from a Neuron C program
is to declare a constant pointer to the block of control addresses for the device. In
the following example, a hypothetical memory-mapped I/O device has two control
registers and a 16-bit data register, at addresses
x , x + 1 , x + 2 , and x + 3 ,
respectively. The device is connected to respond to the addresses of 0x8800 to
0x8803. The fragment of Neuron C code below accesses the device.
typedef struct {
unsigned short int controlReg1;