AT89C5122 ATMEL [ATMEL Corporation], AT89C5122 Datasheet - Page 85

• Manufacturer Part Number: AT89C5122
• Description: MICROCONTROLLER WITH USB AND SMART CARD READER INTERFACES
• Manufacturer: ATMEL [ATMEL Corporation]

Table 51. Smart Card ETU Register 1 - SCETU1 (S:ADh, SCRS=1)
Reset Value = 0XXX X001b
Table 52. Smart Card ETU Register 0 - SCETU0 (S:ACh, SCRS=1)
Reset Value = 0111 0100b
4202D–SCR–06/05
Bit Number
Bit Number
COMP
ETU7
7 - 0
6-3
2-0
7
7
7
Bit Mnemonic
Bit Mnemonic
ETU[10:8]
ETU[7:0]
COMP
ETU6
6
6
-
-
Description
Compensation
Clear this bit when no time compensation is needed (i.e. when the ETU to Card CLK period ratio is close to an
integer with an error less than 1/4 of Card CLK period).
Set this bit otherwise and reduce the ETU period by 1 Card CLK cycle for even bits.
Reserved
The value read from these bits is indeterminate. Do not change these bits.
ETU MSB
Used together with the ETU LSB in SCETU0 (Table 52)
Warning : the ETU counter is reloaded at each register’s write operation.
Do not change this register during character reception or transmission or while Guard Time or Waiting Time
Counters are running.
Description
ETU LSB
The Elementary Time Unit is (ETU[10:0] - 0.5*COMP)/f, where f is the Card CLK frequency.
According to ISO 7816, ETU[10:0] can be set between 11 and 2048 (2047 ?)
The default reset value of ETU[10:0] is 372 (F=372, D=1).
ETU5
5
5
-
ETU4
4
4
-
ETU3
3
3
-
ETU10
ETU2
2
2
ETU9
ETU1
1
1
ETU8
ETU0
0
0
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