Motorola ColdFire MCF5281 - Manual (Page 381)

General Purpose Timer Modules (GPTA and GPTB)
Freescale Semiconductor 20-13
Note: When the fast flag clear all bit, GPTSCR1[TFFCA], is set, any access to the GPT counter registers clears GPT flag register
2.
20.5.14 GPT Channel Registers (GPTCn)
Table 20-16. GPTFLG2 Field Descriptions
Bit(s) Name Description
7 TOF Timer overflow flag. Set when the GPT counter rolls over from 0xFFFF to 0x0000. If
the TOI bit in GPTSCR2 is also set, TOF generates an interrupt request. This bit is
read anytime, write anytime (writing 1 clears the flag, and writing 0 has no effect).
1 Timer overflow
0 No timer overflow
Note: When the GPT channel 3 registers contain 0xFFFF and TCRE is set, TOF does
not get set even though the GPT counter registers go from 0xFFFF to 0x0000. When
TOF is set, it does not inhibit subsequent overflow events.
6–0 — Reserved, should be cleared.
15 0
Field CCNT
Reset 0000_0000_0000_0000
R/W R/W
Address IPSBAR + 0x1A_0010, 0x1A_0012, 0x1A_0014, 0x1A_0016,
0x1B_0010, 0x1B_0012, 0x1B_0014, 0x1B_0016
Figure 20-16. GPT Channel[0:3] Register (GPTCn)
Table 20-17. GPTCn Field Descriptions
Bit(s) Name Description
15–0 CCNT When a channel is configured for input capture (IOSn = 0), the GPT channel registers
latch the value of the free-running counter when a defined transition occurs on the
corresponding input capture pin.
When a channel is configured for output compare (IOSn = 1), the GPT channel
registers contain the output compare value.
To ensure coherent reading of the GPT counter, such that a timer rollover does not
occur between back-to-back 8-bit reads, it is recommended that only word (16-bit)
accesses be used. These bits are read anytime, write anytime (for the output compare
channel); writing to the input capture channel has no effect.
MCF5282 and MCF5216 ColdFire Microcontroller User’s Manual, Rev. 3