AX-SIGFOX Datasheet, PDF (23/30 Pages) ON Semiconductor – Ultra-Low Power Microcontroller

Command Interface
23
Command
Name
AT:SPI[(A|B|C|D)] _{SPI transaction}
=bytes
Description
This command clocks out bytes on the SPI port. The clock
frequency is 312.5kHz. The command returns the bytes read on
MISO during output. Optionally the clocking mode may be
specified (default is A):
Mode
A
B
C
D
Clock Inversion
normal
normal
inverted
inverted
Clock Phase
normal
alternate
normal
alternate
AT:CLK=freq,
reffreq
AT:CLK=OFF
AT:CLK?
AT:DAC=value
AT:DAC=OFF
AT:DAC?
Set clock
generator
Turn off clock
generator
Get clock
generator
Set Σ∆ DAC
Turn off Σ∆ DAC
Note that SEL, if needed, is not generated by this command, and
must instead be driven using standard GPIO commands
(AT:Pn=0|1).
Output a square wave on the pin(s) set to T mode. The frequency
of the square wave is
freq
2¹⁶
×
reffreq
.
Possible
values
for
reffreq
are 20000000, 10000000, 5000000, 2500000, 1250000, 625000,
312500, 156250. Possible values if ffreq are 0…65535.
Switch off the clock generator.
Return the settings of the clock generator. Two numbers are
returned, freq and reffreq.
Output a Σ∆ DAC value on the pin(s) set to T mode. Parameter
value may be in the range –32768..32767. The average output
voltage
is
(1
2
+
value
2¹⁷
)
×
VDD
.
An external low pass filter is needed to get smooth output
voltages. The modulation frequency is 20 MHz. A possible low pass
filter choice is a simple RC low pass filter with R=10kΩ and C=1μF
Switch off the DAC.
Get Σ∆ DAC
Return the DAC value.
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