Manipulating the bits of GPRs. ⢠Checking a bit in GPRs. â Example: LDI. R17,0x0A. ; R17= 0000 1010. SBRS R17,3. ;skip next instruction if Bit 3 in R17 is set.
Dr. Hassan SHARABATY EEE Department, Faculty of Engineering University of Turkish Aeronautical Association
Some Assembler directives: Arithmetic & logic expressions $ULWKPHWLFH[SUHVVLRQV
/',5
/',5
/',5
/',5
/',5
/',5 /',5 /',5
/RJLFH[SUHVVLRQV $1'
/',5[ [
Î /',5[
_ 25
/',5[_[
Î /',5[
A ;25
/',5[A[
Î /',5[
6KLIWRSHUDWRUV /',5[
Î /',5[
!! 6KLIWULJKW /',5[!!
Î /',5[
6KLIWOHIW
2
Some Assembler directives: Arithmetic & logic expressions ([DPSOH 6ROXWLRQ
D :LWKRXWWKHGLUHFWLYHV /',
5[
5
2XW
3257%5
E :LWKWKHGLUHFWLYHV
2U
/',
5 _
5 E_E E
2XW
3257%5
(TX
3%
(TX
3%
/',
5 3% _ 3%
2XW
3257%5
,1&/8'(³0'(),1&´
VHW3%DQG3%
3
Some Assembler directives: HIGH and LOW
/',
5/2: [
/',
5
/',
5+,*+ [
/',
5 +,*+
$GGUHVVRIPHPRU\ORFDWLRQ
/',
5/2:
/',
5
/',
5+,*+
/',
5))
/2:
)) +,*+
([DPSOH
/2:
,QLWLDOL]LQJVWDFNSRLQWHU LDI OUT LDI OUT
R20, SPH, R20, SPL,
HIGH(RAMEND) R20 LOW(RAMEND) R20
5$0(1'
[[[[
0HPRU\ 4
Manipulating the bits of GPRs ¾ &RS\LQJDELW RIDUHJLVWHUWRDVSHFLILFELWRIDQRWKHUUHJLVWHU 65(* VWDWXVUHJLVWHU
1RLQVWUXFWLRQZLOOGRWKDWGLUHFWO\ 9LD7HPSRUDU\IODJ7 7UDQVIHUELW
¾ %67 %LW6WRUHWR 7IODJIURP UHJLVWHU %675GE
VWRUHV ELWE LQ5GWR7IODJ
¾ %/' %LW/RDGIURP 7IODJWR UHJLVWHU %/'5UE
FRSLHVWKH7IODJWRELWELQ5U D3
([DPSOH &RS\ELW IURP5 WRELW LQUHJLVWHU5 %67
5
VWRUHELWIURP5WRWKH7IODJ
%/'
5
FRS\WKH7IODJWRELWLQ5
5
Manipulating the bits of GPRs ([DPSOH $VZLWFKLVFRQQHFWHGWR 3% *HWWKH VWDWXV RIWKDW VZLWFK DQG VDYH LWLQ' RILQWHUQDO 5$0ORFDWLRQ [ 'RQ¶WDIIHFWWKHRWKHUELWVLQWKHPHPRU\[ 6ROXWLRQ &%,
''5%
PDNH 3% DQLQSXW
,1
53,1%
5 3,1%
%67
5
7 3,1%
/'6
5[
/RDGFRQWHQWRIORFDWLRQWR5
%/'
5
5 7
676
[5
&RS\ 5 WRORFDWLRQ 6
Manipulating the bits of GPRs ¾ &KHFNLQJDELW LQ*35V 6%565GE
VNLSQH[WLQVWUXFWLRQLI%LWE LQ5GLVKLJK
6%5&5GE
VNLSQH[WLQVWUXFWLRQLI%LWE LQ5GLVORZ
([DPSOH /',
5[$
5
6%56 5
VNLSQH[WLQVWUXFWLRQLI%LWLQ5LVVHW
/',
WKLVLQVWUXFWLRQZLOOQRWEHH[HFXWHG
5[
6%5& 5
VNLSQH[WLQVWUXFWLRQLI%LWLQ5LVFOHDUHG
/',
5[
ZLOOQRWEHH[HFXWHG
/',
5[ 7
Status register bit-addressability 0DQLSXODWLQJWKHIODJVRI65
8
Status register bit-addressability &KHFNLQJDIODJELW
9
Example: :ULWHDFRGHWRFKHFNLIWKHLQWHUQDO5$0ORFDWLRQ FRQWDLQVDQHYHQ YDOXH
,IVRVHQGLWWR3RUW% ,IQRWPDNHLWHYHQDQGWKHQVHQGLWWR3RUW%
6ROXWLRQ /',5[)) 287''5%5
PDNH3RUW% DQRXWSXW SRUW
$*$,1 /'65[ 6%565
ELWWHVW'VNLSLILW¶VRGGQXPEHU
5-0329(5
LWLVHYHQQXPEHU
&%55E
FOHDUELW'
29(5 2873257%5 -03$*$,1
FRS\LWWR3RUW% ZHFDQXVH5-03WRR 10
Example: :ULWHDFRGHWRFKHFNLIWKHLQWHUQDO5$0ORFDWLRQ FRQWDLQVDQHYHQ YDOXH ,IVRVHQGLWWR3RUW% ,IQRWPDNHLWHYHQDQGWKHQVHQGLWWR3RUW% 6ROXWLRQ /',5[)) 287''5%5
PDNH3RUW% DQRXWSXW SRUW
$*$,1 /'65[ &%55E
FOHDUELW'
2873257%5
FRS\LWWR3RUW%
-03$*$,1
ZHFDQXVH5-03WRR 11
Example: :ULWHDSURJUDPWRVHHLIWKHLQWHUQDO5$0ORFDWLRQFRQWDLQVDQHYHQ YDOXH ,IVRZULWH[LQWRORFDWLRQ ,IQRWZULWH[LQWRORFDWLRQ 6ROXWLRQ /'6
5[
6%5& 5
VNLSQH[WLQVWUXFWLRQLILWLVHYHQ
5-03 2GGBQ
LWLVRGG
/',
5[
676
[5
5-03 +(5( 2GGBQ /', 676 +(5( «
5[ [5 12
Accessing EEPROM in AVR
((3520LVDSODFHWRVWRUHGDWD,WLVQRWGHOHWHGZKHQSRZHULVRII
$7PHJDKDVE\WHVRI((3520
,2UHJLVWHUVWKDWFRQWURO((3520
(('5 ((3520'DWD5HJLVWHU
(($5+ (($5/ ((3520$GGUHVV5HJLVWHU+LJK/RZ
((&5 ((3520&RQWURO5HJLVWHU
13
Accessing EEPROM in AVR
(('5 ((3520'DWD5HJLVWHU
(('5 LVDEULGJHEHWZHHQ((3520DQG&38 :HVKRXOGZULWH GDWDWRWKLVUHJLVWHUEHIRUHWUDQVIHULWWR((3520 $OVRLIZHZDQWWRUHDG IURP((3520ZHKDYHWRUHDGIURP(('5 To write data to EEPROM, you have to write it to the EEDR register and then transfer it to EEPROM. Also, if you want to read from EEPROM you have to read from EEDR. In other words, EEDR is a bridge between EEPROM and CPU.
14
Accessing EEPROM in AVR
((3520 $GGUHVV5HJLVWHU +LJK/RZ (($5+ (($5/
¾ (($5+ (($5/ WRJHWKHU PDNHDELWUHJLVWHUZKLFK SRLQWVWR DGGUHVV RIUHTXHVWHGORFDWLRQLQ((3520 PHPRU\VSDFH
To write data to EEPROM, you have to write it to the EEDR register and then transfer it to EEPROM. Also, if you want to read from EEPROM you have to read from EEDR. In other words, EEDR is a bridge between EEPROM and CPU.
$7PHJDKDVE\WH((3520 ORFDWLRQVÎ ZHQHHGELWVWRDGGUHVV DOOORFDWLRQVLQWKH((3520¶VVSDFH
15
Accessing EEPROM in AVR
((&5 ((3520&RQWURO5HJLVWHU
¾ 7KH((&5 UHJLVWHULVXVHGWRVHOHFW WKHNLQGRIRSHUDWLRQWRSHUIRUPRQ ((3520
To write data to EEPROM, you have to write it to the EEDR register and then transfer it to EEPROM. Also, if you want to read from EEPROM you have to ((5( read ((35205HDG(QDEOH from EEDR. In other words, EEDR is a bridge between EEPROM and CPU. ((:( ((3520:ULWH(QDEOH ((0:( ((35200DVWHU:ULWH(QDEOH ((5,( ((35205HDG\,QWHUUXSW(QDEOH %LWVWRRI((&5DUHXQXVHGDWWKHSUHVHQWWLPHDQG DUHUHVHUYHG
16
Accessing EEPROM in AVR
((&5 ((3520&RQWURO5HJLVWHU
¾ ((5(
Î VWDUWUHDG RSHUDWLRQ LH RQHE\WHRI((3520ZLOO
EHVHQWLQWRWKH(('5 7KH(($5 UHJLVWHUVSHFLILHVWKHDGGUHVVRIWKH GHVLUHGE\WH
To write data to EEPROM, you have to write it to the EEDR register and then transfer it to EEPROM. Also, if you want to read from EEPROM you have to read from EEDR. In other words, EEDR is a bridge between EEPROM and CPU.
17
Accessing EEPROM in AVR
((&5 ((3520&RQWURO5HJLVWHU
¾ ((:(
Î LI((0:(LV HQDEOHGVWDUWWKH ZULWHRSHUDWLRQ LH WKHFRQWHQWRI(('5ZLOOEHVHQWLQWR((3520 7KH(($5 UHJLVWHUVSHFLILHVWKHDGGUHVVRIWKHGHVLUHGE\WH
To write data to EEPROM, you have to write it to the EEDR register and then transfer it to EEPROM. Also, if you want to read from EEPROM you have to read from EEDR. In other words, EEDR is a bridge between EEPROM and CPU.
(('5 ,I((0:( LV]HURVHWWLQJ((:( WR RQHZLOOKDYHQRHIIHFW &DQ,NHHS((0:( WRDOORZDOOZULWLQJUHTXHVWV"
18
Accessing EEPROM in AVR
((&5 ((3520&RQWURO5HJLVWHU
¾ ((0:( FORFNF\FOHV DIWHUPDNLQJ((0:( KDUGZDUHZLOOFOHDUV LW WR]HUR WRSUHYHQWXQZDQWHGZULWHRSHUDWLRQVRQ((3520
To write data to EEPROM, you have to write it to the EEDR register and then transfer it to EEPROM. Also, if you want to read from EEPROM you have to read from EEDR. In other words, EEDR is a bridge between EEPROM and CPU.
5XOH ¾ $WWKHPRPHQWRIVHWWLQJ((0:(
(('5
ZHKDYHFORFNF\FOHVWRVHW 19
((:( WRVWDUWWKHZULWHRSHUDWLRQ
Programming the AVR to Read from EEPROM 1RWH
