ST7LUS5 datasheet(25/124 Pages) STMICROELECTRONICS

25 / 124 page

ST7LUS5, ST7LU05, ST7LU09

Central processing unit

25/124

Interrupt mask

This bit is set by hardware when entering in interrupt or by software to disable all

interrupts except the TRAP software interrupt. This bit is cleared by software.

0: Interrupts are enabled.

1: Interrupts are disabled.

This bit is controlled by the RIM, SIM and IRET instructions and is tested by the JRM

and JRNM instructions.

Note: Interrupts requested while I is set are latched and can be processed when I is

cleared. By default an interrupt routine is not interruptible because the I bit is set by

hardware at the start of the routine and reset by the IRET instruction at the end of the

routine. If the I bit is cleared by software in the interrupt routine, pending interrupts

are serviced regardless of the priority level of the current interrupt routine.

Negative

This bit is set and cleared by hardware. It is representative of the result sign of the

last arithmetic, logical or data manipulation. It is a copy of the 7th bit of the result.

0: The result of the last operation is positive or null.

1: The result of the last operation is negative (that is, the most significant bit is a

logic 1).

This bit is accessed by the JRMI and JRPL instructions.

Zero

This bit is set and cleared by hardware. This bit indicates that the result of the last

arithmetic, logical or data manipulation is zero.

0: The result of the last operation is different from zero.

1: The result of the last operation is zero.

This bit is accessed by the JREQ and JRNE test instructions.

Carry/borrow

This bit is set and cleared by hardware and software. It indicates an overflow or an

underflow has occurred during the last arithmetic operation.

0: No overflow or underflow has occurred.

1: An overflow or underflow has occurred.

This bit is driven by the SCF and RCF instructions and tested by the JRC and JRNC

instructions. It is also affected by the “bit test and branch”, shift and rotate

instructions.

Table 5.

CC register description (continued)

Bit Name

Function

ST7LUS5 数据表(PDF) 25 Page - STMicroelectronics

ST7LUS5 数据表(HTML) 25 Page - STMicroelectronics

Html Pages

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 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

数据表下载