3.4.3.2.1.5 DMCRA – Demodulator Control Register for Path A

This register must only be modified if the block receiving the settings is disabled (RDPR.PRPTA = 1). Modifying the settings during operation may lead to unstable operation.

Name:	DMCRA
Offset:	0x0A6
Reset:	0x00


Bit	7	6	5	4	3	2	1	0
	DMARA	SY1TA	SASKA	DMPGA[4:0]
Access	R/W	R/W	R/W	R/W	R/W	R/W	R/W	R/W
Reset	0	0	0	0	0	0	0	0

Bit 7 – DMARA Demodulator Automatic Restart on Path A

This bit enables a hardware-controlled automatic restart of the demodulator and the subsequent receiving path A.


Bit 7	Description
`0`	The reception and demodulation is continued regardless of error events.
`1`	Reception and demodulation are restarted if any activated condition for the EOTA interrupt is true. The EOTA condition status flags (EOTS[3:0]) and the SOTA condition status flags (SOTSA) are cleared at every restart. The restart is automatically performed by toggling the RDPR.PRPTA bit. The PRPTA bit is not writable while the automatic mode is active.

Bit 6 – SY1TA Symbol Check with 1T only on Path A

Activates a more rigorous check during the symbol timing check.


Bit 6	Description
`0`	The symbol timing check accepts HIGH and LOW times with the selected symbol period (1T) and the double symbol period (2T). Random Manchester data can be used as the preamble in this mode.
`1`	The symbol timing check allows HIGH and LOW times with the selected symbol rate only. This corresponds to an alternating preamble of 1 and 0 symbols. It is a more rigorous criterion and therefore leads to shorter average on-times. The 1T check is performed for the number of bits specified in the SYCSA register. Afterward, 1T and 2T are acceptable (corresponding to random Manchester).

Bit 5 – SASKA Select ASK Input for Path A


Bit 5	Description
`0`	FSK input is selected for receiving path A
`1`	ASK input is selected for receiving path A

Bits 4:0 – DMPGA[4:0] FSK Demodulator PLL Loop Gain for Path A

The correct settings for this register are provided by the configuration tool after selecting the target deviation and data rate for path A. They can also be calculated by using the following procedure:

Calculation of the target PLL loop gain for the maximum symbol rate

S Y M_G A I N_A = 5 \times \frac{S y m b o l R a t e P a t h A}{C L K_B B} ...... (22)

Equation parameters:
- SymbolRatePathA: Maximum expected symbol rate in Hz on the useful signal for path A
- CLK_BB: Baseband clock frequency in Hz. See equation (13) in the section Bandwidth Scaling

Calculation of the target PLL gain for the maximum deviation

D E V_G A I N_A = 10 \times \frac{D e v i a t a i o n R a t e P a t h A}{C L K_B B} ......(23)

Equation parameters:
- DeviationPathA is the maximum expected frequency deviation in Hz of the useful signal for path A
- CLK_BB is the baseband clock frequency in Hz. See equation (13) in the section Bandwidth Scaling
Selection of the required PLL loop gain, which is the larger one of the two gains
$R E Q_P L L_G A I N = \max (S Y M_G A I N_A, D E V_G A I N_A) ......(24)$
Selection of the DMPGA value according to the required PLL loop gain
- The PLL_GAIN_A must be selected from the following table to be greater than or equal to the REQ_PLL_GAIN.
- If REQ_PLL_GAIN ≥ 1, set DMPGA = 16. The corresponding DMPGA value is the correct setting for this register.

Table 3-18. PLL Gain on Path A versus DMPGA Setting
PLL_GAIN_A	DMPGA(Dec)
0.06	0
0.08	1
0.09	2
0.11	3
0.13	4
0.16	5
0.19	6
0.22	7
0.25	8
0.31	9
0.38	10
0.44	11
0.50	12
0.63	13
0.75	14
0.88	15
≥ 1.00	16