PortalPlayer PP502x Device Enable Registers

Overview

The PortalPlayer PP502x SoC have three device enable registers: DEV_EN = 0x6000600c DEV_EN2 = 0x60006010 DEV_EN3 = 0x60006044

Each bit in these registers enables and disables a particular part of the device. Hence, it is thought that this is the key to improving power usage and battery life on these devices. If we can figure out what each bit does, then we can selectively enable and disable bits that we're not using to give a nice battery life boost. This page collects all the information we know so far about these registers.

Known bits

The following bits are already known.

DEV_EN

Bit	Function
0
1	External Device Clocks (according to firmware/drivers/audio/as3514.c:154)
2	System
3	USB0, needs to be set for USB-initialization and when USB is inserted. Otherwise should be unset to save power.
4
5	5G, nano: must be set, otherwise system freezes
6	Serial 0
7	Serial 1
8	5G: enables GPIO?
9
10
11	I2S?
12	I2C?
13
14	ATA
15
16	OPTO/PIEZO
17	4G: backlight PWM
18
19
20
21
22	USB1, needs to be set for USB-initialization and when USB is inserted. Otherwise should be unset to save power.
23	Firewire
24
25	IDE0
26	LCD
27
28
29
30	5G, nano: must be set, otherwise system freezes
31	5G, nano: must be set at startup (otherwise doesn't start), can be unset later

DEV_EN2

Bit	Function
0
1
2
3
4
5	PP5020: ADC
6
7
8
9
10
11
12
13	nano, H10, 4G Color/Photo: LCD
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31

DEV_EN3

Bit	Function
0	5G: must be set, otherwise system freezes
1	5G: must be set, otherwise system freezes
2	5G: must be set, otherwise crash on playback
3	5G: must be set at startup (otherise doesn't reboot into disk mode), can be unset later
4	5G: must be set, otherwise system freezes / Doesn't Boot if unset
5	5G: must be set, otherwise crash on playback
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31

DEV_INIT1

DEV_INIT2

Bit	Function
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30	PP502x: enable PLL
31

Known values for devices