S5L8720/Hardware - Timers

S5L8720 Timer Hardware

Base Address: 0x3C700000

Common Registers

Register	Function
0x118	Timer 4-7 IRQ Status, write to clear interrupt request

IRQ Status Register (0x118)

Bit	Access	Function
2-0	R	Timer 7 Flags (execute handler 1 to 3)
7-3	x	No Function / Unknown
10-8	R	Timer 6 Flags (execute handler 1 to 3)
15-11	x	No Function / Unknown
18-16	R	Timer 5 Flags (execute handler 1 to 3)
23-19	x	No Function / Unknown
26-24	R	Timer 4 Flags (execute handler 1 to 3)
31-27	x	No Function / Unknown

RW: Read/Write Access, x: Don't know

RTC Registers

Register	Function
0x80	RTC Ticks High
0x84	RTC Ticks Low
0x88	On init: 0xA, then after the others: 0x18010
0x8C	On init: 0xFFFFFFFF
0x90	On init: 0xFFFFFFFF
0x94	On init: 0xFFFFFFFF
0x98	On init: 0xFFFFFFFF

Timers

Timer Bases

TimerNumber	0	1	2	3	4	5	6	7
Base	0x0	0x20	0x40	0x60	0xA0	0xC0	0xE0	0x100
Width	16Bit	16Bit	16Bit	16Bit	32Bit	32Bit	32Bit	32Bit

Timer Registers

Register	Name
0x00	Config Register
0x04	Control Register
0x08	Compare Buffer Register (TCMPB)
0x0C	Counter Buffer register (TCNTB)
0x10	10-Bit Prescaler
0x14	Observation Register (TCNTO)

Register Description

Config Register

Bit	Access	Function
2-0	x	No Function / Unknown
3	RW	Switches Bit 23 (TOUT) randomly if set...
4	RW	Compare Mode: Counter runs up to TCMPB (Modebit 0)
5	RW	Auto-Reload: (Modebit 1) 1 = One-Shoot 0 = Interval Mode Counter runs up to TCMPB
6	RW	Clock Select 0 => 133MHz Timer Clock 1 and Divider = 1 and Prescaler = 0 => 133MHz Timer Clock 1 and (Divider > 1 or Prescaler > 0) => 24MHz Timer Clock
7	RW	Unknown
10-8	RW	Divider
11	RW	Invert TOUT
14-12	RW	Unknown
15	x	No Function / Unknown
22-16	x	Unknown
23	RW	Timer Out (TOUT) In mode 0x00: Bit 23 = Toggle when TCNT = 0 In mode 0x01: Bit 23 = (TCNT >= TCMP) In mode 0x10: Bit 23 = (TCNT >= TCMP) In mode 0x11: Bit 23 = Toggle when TCNT = TCMP
24	RW	Counting Direction: 0 = Up, 1 = Down (Only on Timer 4-7)
27-25	x	No Function / Unknown
28	RW	When counting down, count down starting at TCMPB (Only on Timer 4-7)
31-29	x	No Function / Unknown

RW: Read/Write Access, x: Don't know

Control Register

Bit	Access	Function
0	RW	Start / Stop
1	RW	Manual Update
3-2	x	No Function/ Unknown
4	RW	Resets all counter registers to 0
31-5	x	No Function/ Unknown

RW: Read/Write Access, x: Don't know

References

Information gathered from:

• Reversing iBoot
• openiBoot
• Playing with the registers when iBoot is running

The bootloader on iOS devices and some later iPods, or a general name for the pre-kernel boot process