Maxim Integrated DS4830A Optical Microcontroller - Manual (Page 135)

DS4830A User’s Guide
135
14.3.2.2 – Local Register PWMCFGn (through PWMDATA [15:0]
Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Name INV - ALT_
LOC
PWMEN - CLK_SEL - PS1 PS0 RES[3:0]
Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Access rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw
PWMCN REG_SEL = 01b
PWMDATA[15:0]  PWMCFGn[15:0]
BIT NAME DESCRIPTION
15 INV Invert PWM Output. When this bit is set to ‘1’, PWM output is inverted for the selected
PWM channel (determined by the PWM_SEL[3:0] bits).
14 - Reserved. The user should not write to this bit.
13 ALT_LOC Alternate Location: PWM outputs at channels 0 to 7 are multiplexed with the DAC
outputs. By default, the PWM outputs appear at the DAC outputs. When ALT_LOC bit is
set to ‘1’, the PWM outputs will appear at the alternate location (See Table 14-3 for
details).
12 PWMEN Local Enable: Setting this bit to ‘1’ will enable the individual PWM channel. PWM
operation will be enabled only when both local enable and the Master Enable M_EN in
PWMCN are enabled. Setting this bit to ‘0’ will disable the individual PWM channel.
11:10 - Reserved. The user should not write to these bits.
9:8 CLK_SEL[1:0] Clock Select. These bits select the PWM clock for the selected PWM channel (which is
selected by PWM_SEL[3:0] bits).
CLK_SEL PWM Clock Source
00b Core Clock
01b Peripheral Clock
1xb External Clock
The external clock range is 20MHz to 133MHz.
7:6 - Reserved. The user should not write to these bits.
5:4 PS[1:0] Pulse Spreading: These bits enable pulse spreading. The number of slots in a PWM
frame is defined by these bits along with resolution.
PS[1:0] Pulse spreading
00b Resolution / 2
10
01b Resolution / 2
9
10b Resolution / 2 8
11b Resolution / 2
7
3:0 RES[3:0] Resolution Select. These bits are used to configure PWM resolution (in bits) for selected
PWM channel (which is selected by PWM_SEL[3:0] bits). The PWM Frame frequency is
determined by the clock Frequency programmed and the resolution selected.
N
Frequency Clock PWM
Frequency Frame PWM
2
=
Where N is the selected resolution.
RES [3:0] PWM Resolution bits
0000b 7
0001b 8
0010b 9
0011b 10
0100b 11
0101b 12
0110b 13
0111b 14
1000b 15
>=1001b 16