什么是最大DMA/PMP速度？

嗨，我有一个项目与32 x128 RGB LED矩阵。我已经使用比特敲击和DMA/PMP发送数据给它。我认为使用DMA/PMP会更快，但情况并非如此。我必须为每个帧发送8个“子帧”——每一个颜色的子帧，因为LED锁存电路是开或关，不是PWMD或任何东西。它的工作，但似乎PMP将不会输出任何比8HMZ快，所以我不能得到相当的帧数我想要的。默认的PBLK2设置是SysCLK／2，因此应该是100MHz？所以，它不应该能够用正确的PMP等待状态设置做得比8HMZ快吗？我甚至尝试制作PBLK2 SysCLK／1。100MHz是否太快？它说，EBI和SQI max是50MHz，但它不表示最大的PMP/DMA。这是不是更快的DMA/PMP将去？请让我知道，并提前感谢。这是我的初始化代码：



      以下为原文

    Hi,

  I have a project with a 32x128 RGB LED matrix.  I've sent data to it using both bit-banging and DMA/PMP.  I thought using DMA/PMP would be faster, but it doesn't look like that's the case.  I have to send 8 "sub-frames" for every frame - one sub-frame for each bit of color, because the LED latch circuitry is either on or off, not PWMd or anything.  It's working, but it appears the PMP won't output any faster than 8HMz, so I can't get quite the framerate I wanted.  The default PBCLK2 setting is SYSCLK/2, so it should be 100MHz?, so shouldn't it be able to do faster than 8HMz with the right PMP wait state settings?  I even tried making PBCLK2 SYSCLK/1.  Is 100MHZ too fast?  It says EBI and SQI max is 50MHz, but it doesn't state a max for PMP/DMA.  Is this all the faster DMA/PMP will go?  Please let me know and thanks in advance.  Here's my init code:


void InitDMA()
{
DMACONbits.ON = 1; // enable the DMA controller
// DMA Channel 0...
IEC4bits.DMA0IE = 0; // disable DMA Channel 0 interrupts
IFS4bits.DMA0IF = 0; // clear any existing DMA Channel 0 interrupt flag
DCH0CON = 0x3; // turn channel off, set to priority 3, no chaining
DCH0ECON = 0; // no start or stop IRQ, no pattern match
DCH0SSA = _VirtToPhys((const void*)dispfbptr); // transfer source physical address
DCH0DSA = _VirtToPhys((const void*)&PMDIN); // transfer destination physical address
DCH0SSIZ = H_COLS; // source size
DCH0DSIZ = 1; // destination size
DCH0CSIZ = 1; // number of byte(s) transferred per event
DCH0ECONbits.CHSIRQ = _TIMER_1_VECTOR; // Set Channel Transfer Start IRQ to Timer 1
DCH0ECONbits.SIRQEN = 1; // 1 = Start channel cell transfer if an interrupt matching CHSIRQ occurs
DCH0INTCLR = 0x00ff00ff; // clear existing events, disable all interrupts
DCH0INTSET = 0x00090000; // enable Block Complete and error interrupts
IPC33bits.DMA0IP = 3; // set DMA Channel 0 priority to 3
IPC33bits.DMA0IS = 1; // set DMA Channel 0 sub-priority to 1
IEC4bits.DMA0IE = 1; // enable DMA channel 0 interrupt
DCH0CONbits.CHAEN = 1; // turn DMA Channel 0 on
DCH0CONbits.CHEN = 1; // turn DMA Channel 0 on
}
void InitPMP()
{
// PMP initialization...
PMCON = 0; // Stop and configure PMCON register for Address mode.
PMCONbits.ON = 0; // Stop and configure PMCON register for Address mode.
IEC4bits.PMPEIE = 0; // Disable PMP interrupt in case it is already enabled
PMCONbits.PTWREN = 1; // Enable the Write Strobe Port (PTWREN = 1).
PMCONbits.PTRDEN = 0; // Enable the Read Strobe Port (PTRDEN = 1).
PMCONbits.WRSP = 1; // Write Strobe Polarity active low.
PMCONbits.RDSP = 0; // Read Strobe Polarity active low.
PMCONbits.CSF = 0; // both Chip Select bits act as address lines.
PMCONbits.ADRMUX = 0; // address and data appear on separate pins.
PMCONbits.DUALBUF = 0; // Use separate registers for reads and writes.
PMMODEbits.IRQM = 1; // interrupt generated at end of read/write cycle.
PMMODEbits.INCM = 0; // Set the Increment Mode to increment (INCM = 00)
PMMODEbits.MODE16 = 0; // Set the mode to 8 bits (MODE16 = 0).
PMMODEbits.MODE = 2; // Set the mode Master Mode 2 - separate read/write lines (MODE = 10).
PMMODEbits.WAITM = 0; // Set the Data Read/Write Strobe Wait State to 1 Tpb (WAITM = 0000)
PMMODEbits.WAITB = 0; // Set the Data Setup To Read/Write Strobe Wait State to 1 Tpb (WAITB = 00)
PMMODEbits.WAITE = 0; // Set the Data Hold After Read/Write Strobe Wait States to 1 Tpb (WAITE = 00)
PMAEN = 0x0;// Disable all address and Chip Select lines (they will function as port I/O.
PMCONbits.ON = 1; // Enable the PMP module
}