User’s Manual

 

 

 

 

 

 

IBM PowerPC 750GX and 750GL RISC Microprocessor

 

 

 

 

 

 

Table 2-3. Valid THRM1/THRM2 Bit Settings

 

 

 

 

 

 

 

TIN1

TIV1

TID

TIE

 

V

Description

 

 

 

 

 

 

 

x

x

x

x

 

0

Invalid entry. The threshold in the SPR is not used for comparison.

 

 

 

 

 

 

 

x

x

x

0

 

1

Disable thermal-management interrupt assertion.

 

 

 

 

 

 

 

 

 

 

 

 

 

Set TIN and assert thermal-management interrupt if TIE = 1 and the junction temper-

x

x

0

x

 

1

ature exceeds the threshold. If TIE = 0, then no interrupt will be taken when the

 

 

 

 

 

 

threshold is achieved.

 

 

 

 

 

 

 

x

x

1

x

 

1

Set TIN and assert thermal-management interrupt if TIE = 1 and the junction temper-

 

ature is less than the threshold.

 

 

 

 

 

 

 

 

 

 

 

 

 

x

0

x

x

 

1

The state of the TIN bit is not valid.

 

 

 

 

 

 

 

0

1

0

x

 

1

The junction temperature is less than the threshold and as a result the thermal-man-

 

agement interrupt is not generated for TIE = 1.

 

 

 

 

 

 

 

 

 

 

 

 

 

1

1

0

x

 

1

The junction temperature is greater than the threshold and as a result the thermal-

 

management interrupt is generated if TIE = 1.

 

 

 

 

 

 

 

 

 

 

 

 

 

0

1

1

x

 

1

The junction temperature is greater than the threshold and as a result the thermal-

 

management interrupt is not generated for TIE = 1.

 

 

 

 

 

 

 

 

 

 

 

 

 

1

1

1

x

 

1

The junction temperature is less than the threshold and as a result the thermal-man-

 

agement interrupt is generated if TIE = 1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1. TIN and TIV are read-only status bits.

 

 

 

 

 

 

 

 

 

2.1.4.2 Thermal-Management Register 3 (THRM3)

The THRM3 register is used to enable the thermal assist unit and to control the timing of the output sample comparison. The thermal assist logic manages the thermal-management interrupt generation and time-multiplexed comparisons in dual-threshold mode, as well as other control functions.

The THRM registers can be accessed with the mtspr and mfspr instructions using the following SPR numbers:

•THRM1 is SPR 1020

•THRM2 is SPR 1021

•THRM3 is SPR 1022

 

 

 

 

 

 

 

Reserved

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SITV

 

 

 

 

 

 

 

 

E

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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

31

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bits

 

 

 

 

Field Name

 

 

 

 

 

 

 

 

 

 

 

 

 

Description

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0:14

 

 

 

 

Reserved

 

 

 

Reserved for future use. System software should clear these bits when writing to THRM3.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Sample interval timer value. Number of elapsed processor clock cycles before a junction

 

 

 

 

 

 

 

 

 

 

 

 

temperature versus threshold comparison result is sampled to set the TIN bit and gener-

 

 

15:30

 

 

 

SITV

 

 

 

ate an interrupt. This is necessary due to the thermal sensor, the digital-to-analog con-

 

 

 

 

 

 

 

 

verter (DAC), and because the analog comparator settling time is greater than the

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

processor cycle time. The value should be configured to allow a sampling interval of 20

 

 

 

 

 

 

 

 

 

 

 

 

microseconds.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

31

 

 

 

 

 

E

 

 

 

Enables the thermal sensor compare operation if either THRM1[V] or THRM2[V] is set.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

gx_02.fm.(1.2)

Programming Model

March 27, 2006

Page 79 of 377