大家好:
我想请问个问题,我们自己设计的板子,处理器是TM4C1292NCZAD,扩展了一块512M SDRAM,型号为IS42S16320D-7BLI,使用TIDM-TM4C129XSDRAM提供的原理图设计, 并使用例程测试读写性能远不如TIDM-TM4C129XSDRAM文档里面的那么高,
以下为我们板子的测试数据,跟TIDM-TM4C129XSDRAM测试差了一半还多呢.请问是为什么呀.我们使用示波器测试EPI0_31 引脚 , 时钟频率是60Mhz.
System Initialize
-----------------------------------------
System Clock Freq: 120Mhz
Initialize Console.....................OK
Initialize uDMA Controller.............OK
-----------------------------------------
Startup completed
EPI SDRAM Mode ->
Type: SDRAM
Starting Address: 0x60000000
End Address: 0x6fffffff
Data: 16-bit
Size: 256MB (32Meg x 16bits)
SDRAM Initial Data:
Mem[0x6000.0000] = 0x1234
Mem[0x6000.0001] = 0xabcd
Mem[0x6FFF.FFFE] = 0xdcba
Mem[0x6FFF.FFFF] = 0x4321
SDRAM Write:
Mem[0x6000.0000] <- 0xabcd
Mem[0x6000.0001] <- 0x1234
Mem[0x6FFF.FFFE] <- 0xdcba
Mem[0x6FFF.FFFF] <- 0x4321
SDRAM Read:
Mem[0x6000.0000] = 0xabcd
Mem[0x6000.0001] = 0x1234
Mem[0x6FFF.FFFE] = 0xdcba
Mem[0x6FFF.FFFF] = 0x4321
Read and write to external SDRAM was successful!
Begin Performance Test!
16-bit SDRAM Write : 13.49062 MBps
16-bit SDRAM Read : 07.90099 MBps
32-bit SDRAM Write : 20.20320 MBps
32-bit SDRAM Read : 13.62328 MBps
64-bit SDRAM Write : 36.11910 MBps
64-bit SDRAM Read : 19.39513 MBps
