AT83C5122_08 ATMEL [ATMEL Corporation], AT83C5122_08 Datasheet - Page 147

• Manufacturer Part Number: AT83C5122_08
• Description: C51 Microcontroller with USB and Smart Card Reader Interfaces
• Manufacturer: ATMEL [ATMEL Corporation]

Mode 2 (8-bit Timer with Auto-
Reload)
4202F–SCR–07/2008
INTx#
CK_Tx
INTx#
CK_Tx
Tx
Tx
TMOD reg
TMOD reg
GATEx
GATEx
/6
/6
Figure 91. Timer/Counter x (x = 0 or 1) in Mode 1
Figure 92. Mode 1 Overflow Period Formula
Mode 2 configures Timer 0 as an 8-bit Timer (TL0 register) that automatically reloads
from the TH0 register (see Figure 93). TL0 overflow sets the TF0 flag in the TCON reg-
ister and reloads TL0 with the contents of TH0, which is preset by the software. When
the interrupt request is serviced, the hardware clears TF0. The reload leaves TH0
unchanged. The next reload value may be changed at any time by writing it to the TH0
register.
Figure 94 gives the autoreload period calculation formula when in timer mode.
Figure 93. Timer/Counter x (x = 0 or 1) in Mode 2
Figure 94. Mode 2 Autoreload Period Formula
TFx
TFx
TMOD reg
PER
PER
C/Tx#
=
=
0
1
TCON reg
TCON reg
6 (256 – THx)
6
TRx
TRx
(65536 – (THx, TLx))
F
CK_Tx
TMOD reg
C/Tx#
F
0
1
CK_Tx
AT83R5122, AT8xC5122/23
(8 bits)
THx
(8 bits)
(8 bits)
THx
TLx
(8 bits)
TLx
Overflow
Overflow
TCON reg
TCON reg
TFx
TFx
Timer x
Interrupt
Request
Timer x
Interrupt
Request
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