MC13201 Technical Data, Rev. 1.1,

24

Freescale Semiconductor

8.6

Controlling RF Modes of Operation

Use of the RF interface pins and RF modes of operation are controlled through several bits of modem

Control_B Register 07. Figure 15 shows the model for Register 07 with the RF interface control bits

highlighted.

Figure 15. Control_B Register 07 Model

The RF interface control bits include:

•

RF_switch_mode (Bit 12) - This bit selects Dual Port Mode versus Single Port Mode:

— The default condition (Bit 12 = 0) is Dual Port Mode where the RF inputs are RFIN_M and

RFIN_P and the RF outputs are PAO_M and PAO_P, and operation is as described in

Section 8.5.2, “Dual Port Operation. The use of CT_Bias pin in Dual Port Mode is controlled

by Bit 13 and Bit 12.

— When Bit = 1, the Single Port Mode is selected where RFIN_M (PAO_M) and RFIN_P

(PAO_P) become bidirectional pins and operation is as described in Section 8.5.1, “Single Port

Operation. The use of CT_Bias pin in Dual Port Mode in controlled by Bit 13 and Bit 12.

•

Ct_bias_en (Bit 14) - This bit is the enable for the CT_Bias output. When Bit 14 = 0 (default), the

CT_Bias is disabled and stays in a Hi-Z or tri-stated condition. When Bit 14 = 1, the CT_Bias

output is active and its state is controlled by the selected mode (Bit 12), ct_bias_inv, and operation

of the radio.

•

Ct_bias_inv (Bit 13) - This bit only affects the state of CT_Bias when Dual Port Mode is selected

and CT_bias is active. The CT_Bias changes state in Dual Port Mode based on the TX or RX state

of the radio. The ct_bias_inv bit causes the sense of the active state to change or invert based on

Bit 13’s setting. In this manner, the user can select the CT_Bias as a control signal for external

components and make the control signal active high or active low.

Register 07

0x07

BIT

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

TYPE

r/w r/w r/w r/w r/w

r/w

r/w r/w r/w

r/w

r/w

RESET

0

0

0

0

1

1

0

0

0

0

0

0

0

0

0

0

0x0C00