AN370
Rev. 1.0
25
6.4. Transmission Chain Control
The transmission chain uses the LC oscillator, DIV divider, and the PA power amplifier. Those blocks are referred
to as LC, DIV, and PA, respectively. They are controlled by the output serializer ODS when it is turned on by
vOds_Enable(1) call. The sequence how the blocks are controlled is based on the selected mode (OOK/FSK) and
selected data rate.
The blocks can be also forced to be on by using the ODS_CTRL register or, preferably, API functions. The force
settings have higher priority than the control from the data stream. The forced on and data controls are
independent and are logically OR-ed together.
Since the blocks require some time to stabilize before their output can be used, some API functions turn those
blocks on and leave them forcibly enabled. The purpose of doing that is to save the startup time in the application.
The API functions which do that should be followed by API functions which actually take advantage of the fact that
some of those blocks were left on.
It takes 130 µs for the LC to stabilize and 10 µs for the DIV to stabilize.
Table 4 shows the transmission chain control functions controlling the state of LC, DIV, and PA.
Table 4. Transmission Chain Control Functions
Function
LC
DIV
PA
Notes
Functions
vFCast_Tune
1
1, 0
—
Leaves the LC forcibly on. Assumes that
the ODS is disabled.
vPa_Tune
1, 0
1, 0
1, 0
Calls vSys_ForceLc, forces all “on” and
then clears the forced “on” bits. Assumes
that the ODS is disabled.
vOds_Enable
*
*
*
Enable/Disable ODS for data transmission.
vStl_PreLoop
1+, 1*
1*
1*
Calls vSys_ForceLc() but only for high data
rates (+ designation), then calls
vOds_Enable(1) to enable ODS for data
transmit.
vStl_PostLoop
0, 0*
0*
0*
Calls vOds_Enable(0) to disable ODS for
data transmit.
Notes:
*: The asterisk means the block enable values are controlled from the ODS data path based on the fact that the ODS is
enabled (1*) or disabled (0*). The values without “*” denote the forced block enable values controlled by the ODS_CTRL
bits.
S, 1, R: Save the original setting upon entry, force value to 1 for function processing, then restore the original value before
return.
1: Set the forced block enable value to 1.
1+: Set the forced block enable value to 1 depending on some other device setting.
1*: Block enable is controlled from the ODS data path setting (ODS is enabled).
1, 0: Set the forced block enable value to 1, then 0.
0, 0*: Set the forced block enable value to 0, after that the block is controlled by the 0 setting from the ODS data path (ODS
is disabled.
—: The function does not effect status of this block.