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MC9S12P64CFT 参数 Datasheet PDF下载

MC9S12P64CFT图片预览
型号: MC9S12P64CFT
PDF下载: 下载PDF文件 查看货源
内容描述: 微控制器 [Microcontrollers]
分类和应用: 微控制器外围集成电路时钟
文件页数/大小: 566 页 / 7414 K
品牌: FREESCALE [ Freescale ]
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S12S Debug Module (S12SDBGV2)  
Field3 Bits in Compressed Pure PC Modes  
Table 6-41. Compressed Pure PC Mode Field 3 Information Bit Encoding  
INF1  
INF0  
TRACE BUFFER ROW CONTENT  
0
0
1
1
0
1
0
1
Base PC address TB[17:0] contains a full PC[17:0] value  
Trace Buffer[5:0] contain incremental PC relative to base address zero value  
Trace Buffer[11:0] contain next 2 incremental PCs relative to base address zero value  
Trace Buffer[17:0] contain next 3 incremental PCs relative to base address zero value  
Each time that PC[17:6] differs from the previous base PC[17:6], then a new base address is stored. The  
base address zero value is the lowest address in the 64 address range  
The first line of the trace buffer always gets a base PC address, this applies also on rollover.  
6.4.5.5  
Reading Data from Trace Buffer  
The data stored in the Trace Buffer can be read provided the DBG module is not armed, is configured for  
tracing (TSOURCE bit is set) and the system not secured. When the ARM bit is written to 1 the trace buffer  
is locked to prevent reading. The trace buffer can only be unlocked for reading by a single aligned word  
write to DBGTB when the module is disarmed.  
The Trace Buffer can only be read through the DBGTB register using aligned word reads, any byte or  
misaligned reads return 0 and do not cause the trace buffer pointer to increment to the next trace buffer  
address. The Trace Buffer data is read out first-in first-out. By reading CNT in DBGCNT the number of  
valid lines can be determined. DBGCNT does not decrement as data is read.  
Whilst reading an internal pointer is used to determine the next line to be read. After a tracing session, the  
pointer points to the oldest data entry, thus if no rollover has occurred, the pointer points to line0, otherwise  
it points to the line with the oldest entry. In compressed Pure PC mode on rollover the line with the oldest  
data entry may also contain newer data entries in fields 0 and 1. Thus if rollover is indicated by the TBF  
bit, the line status must be decoded using the INF bits in field3 of that line. If both INF bits are clear then  
the line contains only entries from before the last rollover.  
If INF0=1 then field 0 contains post rollover data but fields 1 and 2 contain pre rollover data.  
If INF1=1 then fields 0 and 1 contain post rollover data but field 2 contains pre rollover data.  
The pointer is initialized by each aligned write to DBGTBH to point to the oldest data again. This enables  
an interrupted trace buffer read sequence to be easily restarted from the oldest data entry.  
The least significant word of line is read out first. This corresponds to the fields 1 and 0 of Table 6-37. The  
next word read returns field 2 in the least significant bits [3:0] and “0” for bits [15:4].  
Reading the Trace Buffer while the DBG module is armed returns invalid data and no shifting of the RAM  
pointer occurs.  
6.4.5.6  
Trace Buffer Reset State  
The Trace Buffer contents and DBGCNT bits are not initialized by a system reset. Thus should a system  
reset occur, the trace session information from immediately before the reset occurred can be read out and  
the number of valid lines in the trace buffer is indicated by DBGCNT. The internal pointer to the current  
S12P-Family Reference Manual, Rev. 1.13  
186  
Freescale Semiconductor  
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