Echelon I/O Model Reference for Smart Transceivers and Neuron Chips - Manual (Page 121)

I/O Model Reference 111
Up to 255 bytes can be bi-directionally transferred at a time. This I/O model
depends on interrupts to process data at high speed and does not use the io_in()
and io_out() function calls. After transfer is initiated, control is returned to the
application immediately, and the application needs to poll the I/O model for
completion. Transfers can be suspended and resumed by disabling and enabling
interrupts. Turning off interrupts might be required when going off-line, or for
assuring that other time-critical application execution is not disturbed by
background interrupts. Additionally, transfers can be aborted.
[default] (CPOL = 1)
Present bit
Sample bit
Invert (CPOL = 0)
SS
MISO
MOSI msb lsb bit5 bit4 bit6 bit2 bit3 bit1
msb lsb bit5 bit4 bit6 bit2 bit3 bit1
Figure 39. Transmission Timing for Clockedge(-) (CPHA : 0)
[default] (CPOL = 1)
Present bit
Sample bit
invert (CPOL = 0)
SS
MISO
MOSI msb lsb bit5 bit4 bit6 bit2 bit3 bit1
msb lsb bit5 bit4 bit6 bit2 bit3 bit1
Figure 40. Transmission Timing for Clockedge(+) (CPHA : 1)