SWRS045F January 2006 – November 2018 CC1021
PRODUCTION DATA.
The CC1021 device has a built-in test pattern generator that generates a PN9 pseudo random sequence. The PN9_ENABLE bit in the MODEM register enables the PN9 generator. A transition on the DIO pin is required after enabling the PN9 pseudo random sequence.
The PN9 pseudo random sequence is defined by the polynomial x9 + x5 + 1.
The PN9 sequence is ‘XOR’ed with the DIO signal in both TX and RX mode as shown in Figure 5-31. Hence, by transmitting only zeros (DIO = 0), the BER (Bit Error Rate) can be tested by counting the number of received ones.
NOTE
The nine first received bits should be discarded in this case. Also, one bit error will generate three received bit errors.
Transmitting only ones (DIO = 1), the BER can be tested by counting the number of received zeroes.
The PN9 generator can also be used for transmission of ‘real-life’ data when measuring narrowband ACP (Adjacent Channel Power), modulation bandwidth or occupied bandwidth.