HT98R068-1 Two-way Radio OTP MCU
System Clock Switches
In the system setup preliminary stage, the operating frequency controlled by two groups of
registers, CTRL2 [7-5, 3-0] and CTRL0 [0] is firstly selected. The description is as follows:
System Control Register 2 (CTRL2)
Bit
7
6
5
4
3
2
1
0
CTRL2 M1 M0 PLLD2
AUPRST
PLLEN
PLLD1
PLLD0 LXTEN
POR 0 0 1
0
0
1
1
0
CTRL2 [3]: ON/OFF PLL mode 1. This bit controls the PLL on/off. The CTRL2 [7-6] bits
select the PLL ascending frequency which has four system frequencies to meet different
application requirmennts. The CTRL2 [5] bit selects the PLL divider ratio of the audio
processor with one and two times provided. The CTRL2 [2-1] bits is the MCU PLL
divider/multiplier select bits with 1, 2, 4 ratio selections. The CTRL2 [0] bit is LXT low
speed selection bit, which can request the system to enter the IDLE mode when used
together with HALT instruction.
System Control Register 0 (CTRL0)
Bit
7
6
5
4
3
2
1
0
CTRL0 PCFG PFDCS
-
-
- PFDC LXTLP CLKMOD
POR 0 0 - - - 0 0
1
The CTRL0 [0] bit selects the MCU high speed mode. If CTRL0 [0] =1, the MCU operates
in the low speed mode (32,768kHz). If CTRL0 [0] = 0, the MCU operates in the PLL mode.
When using the PLL mode, it is important to note that when the PLL is enabled the PLL
ascending frequency ratio, MCU and audio processor divider ratio must be first selected
after which a delay of 10ms (PLL stabilising time) mus be implemented before allowing it
to be a device clock source. When the MCU is on by using the CTRL0 [0] bit and the
audio processor is turned on by using the CTRL2 [4] bit, the MCU operates in the PLL
mode, it is not recommended that change the PLL divider setting.
MCU
Audio Processor
PLLD1 , PLLD0
PLLD2
PLLEN
M1,M0
PLL
Speed
0,1 (÷1)
1,0 (÷2)
1,1 (0,0)
0 (÷1)
1 (÷2)
0 X
32.768K
32.768K
32.768K
1 00
8.192M
8.192M
4.096M
2.048M
8.192M 4.096M
1 01
10.24M
10.24M
5.12M
2.56M 10.24M 5.12M
1 10
12.288M
12.288M
6.144M
3.072M
12.288M 6.144M
1 11
16.384M
16.384M
8.192M
4.096M
16.384M 8.192M
X: Don’t care
MCU & Audio Procrssor PLL Divider Table
4