
19
AT89C51RB2/RC2
4180E–8051–10/06
Table 16. CKCON1 Register
CKCON1 - Clock Control Register (AFh)
Reset Value = XXXX XXX0b
Not bit addressable
76
54
32
1
0
--
---
--
SPIX2
Bit
Number
Bit
Mnemonic
Description
7-
Reserved
6-
Reserved
5-
Reserved
4-
Reserved
3-
Reserved
2-
Reserved
1-
Reserved
0SPIX2
SPI (This control bit is validated when the CPU clock X2 is set; when X2 is low,
this bit has no effect).
Clear to select 6 clock periods per peripheral clock cycle.
Set to select 12 clock periods per peripheral clock cycle.