stm32f429主频为180MHz, sdramz做lcd缓存时,刷完一帧图片,部分像素点颜 {MOD}发送了变化,如下图。但将主频设置为160MHz时图片显示又很稳定,后来测试了一下sdram,发现
主频大于160M,并且随着主频的增大,sdram的数据越不稳定。而160M时数据
又很稳定,有没有人遇到这样的问题呢?会不会是sdram的布线不好引起的?
sdram配置如下:
[mw_shl_code=c,true]/* FMC SDRAM Bank configuration */
/* Timing configuration for 90 Mhz of SD clock frequency (180Mhz/2) */
/* TMRD: 2 Clock cycles */
FMC_SDRAMTimingInitStructure.FMC_LoadToActiveDelay = 2;
/* TXSR: min=70ns (7x11.11ns) */
FMC_SDRAMTimingInitStructure.FMC_ExitSelfRefreshDelay = 7;
/* TRAS: min=42ns (4x11.11ns) max=120k (ns) */
FMC_SDRAMTimingInitStructure.FMC_SelfRefreshTime = 4;
/* TRC: min=70 (7x11.11ns) */
FMC_SDRAMTimingInitStructure.FMC_RowCycleDelay = 7;
/* TWR: min=1+ 7ns (1+1x11.11ns) */
FMC_SDRAMTimingInitStructure.FMC_WriteRecoveryTime = 2;
/* TRP: 20ns => 2x11.11ns */
FMC_SDRAMTimingInitStructure.FMC_RPDelay = 2;
/* TRCD: 20ns => 2x11.11ns */
FMC_SDRAMTimingInitStructure.FMC_RCDDelay = 2;
/* FMC SDRAM control configuration */
FMC_SDRAMInitStructure.FMC_Bank = FMC_Bank2_SDRAM;
/* Row addressing: [7:0] */
FMC_SDRAMInitStructure.FMC_ColumnBitsNumber = FMC_ColumnBits_Number_8b;
/* Column addressing: [11:0] */
FMC_SDRAMInitStructure.FMC_RowBitsNumber = FMC_RowBits_Number_12b;
FMC_SDRAMInitStructure.FMC_SDMemoryDataWidth = SDRAM_MEMORY_WIDTH;
FMC_SDRAMInitStructure.FMC_InternalBankNumber = FMC_InternalBank_Number_4;
FMC_SDRAMInitStructure.FMC_CASLatency = SDRAM_CAS_LATENCY;
FMC_SDRAMInitStructure.FMC_WriteProtection = FMC_Write_Protection_Disable;
FMC_SDRAMInitStructure.FMC_SDClockPeriod = SDCLOCK_PERIOD;
FMC_SDRAMInitStructure.FMC_ReadBurst = SDRAM_READBURST;
FMC_SDRAMInitStructure.FMC_ReadPipeDelay = FMC_ReadPipe_Delay_1;
FMC_SDRAMInitStructure.FMC_SDRAMTimingStruct = &FMC_SDRAMTimingInitStructure;[/mw_shl_code]
只要每个数据连续写2或3次在读就不会出错,只写一次(>160mhz)必出错,不知道是什么原因
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我测试过写入然后马上读出来没问题,过一段时间读出来部分数据就变了,现在只能降低sdram的时钟,主频180M,sdram时钟设置为主频的3分频(官方例程为2分频),这样sdram数据就没有出错了,如果要用lcd控制器,还要将sdram的TRP(预充电有效周期)改小点,还有lcd的时钟也改小点,不然屏幕会抖动,至于为什么sdram时钟大于80M数据就不稳定,暂时还没有找到原因
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F429这么不给力?
之前ST宣讲会看别人的驱动,还挺好啊。
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