PIC18F4550上的USB SIE的UCON.PPBRST操作如何设置？

当我使用乒乓缓冲时，我启用了在UBS.CONFIG.h中的选项，并信任MLA来处理细节；-读取数据表，在PPBRST中有一行：“PPBRST必须在固件中清除”（DS9632 Rev E，第167页，第一段）。我将解释这意味着只要设置了位，乒乓缓冲就被禁用，并且只使用偶数缓冲器。MLA在配置期间断言比特，然后一旦配置就关闭。例如，这是来自MLA UBS.Engult.C线1981～1997：HTH，D。



      以下为原文

    When I use ping pong buffering, I enable the option in u***_config.h and trust the MLA to handle the details ;-)
 
Reading the datasheet, there is a line in the PPBRST: "PPBRST must be cleared in firmware" (DS39632 rev E, page 167, first paragraph).  I would interpret that to mean that as long as the bit is set, ping-pong buffering is disabled and would only use the even buffers.  The MLA asserts the bit during configuration and then turns if off once configured.
 
For example this is from the MLA u***_device.c lines 1981-1997:

// Assert reset request to all of the Ping Pong buffer pointers
USBPingPongBufferReset = 1;
//Re-Initialize all ping pong software state bits to 0 (which corresponds to
//the EVEN buffer being the next one that will be used), since we are also
//doing a hardware ping pong pointer reset above.
for(i = 0; i < (uint8_t)(USB_MAX_EP_NUMBER+1u); i++)
{
ep_data_in.Val = 0u;
ep_data_out.Val = 0u;
}
//clear the alternate interface settings
memset((void*)&USBAlternateInterface,0x00,USB_MAX_NUM_INT);
//Stop trying to reset ping pong buffer pointers
USBPingPongBufferReset = 0;

 
HTH,
D

丹诺，谢谢你的回答！说PPBRST强制SIE在设定时甚至使用BD是正确的吗？如果被清除后，SIE会先使用偶数，然后使用奇数的BD吗？为什么它是如此混乱的USB？：）



      以下为原文

    Danno, thanks for the answer!
 
Would it be correct to say that PPBRST forces SIE to use even BD's when set?
 
If cleared after being set, will SIE first use even and then odd BD's?
 
Why is it such a mess with USB? :)
 

“PPBRST迫使SIE在设定时甚至使用BD是否正确？”对。这就是我解释数据表的方式。“如果设置完毕，SIE会先使用偶数，然后使用奇数的BD吗？”也许，但你为什么在乎？USTAT寄存器，它告诉固件关于最后一个事务，包括PPBI位。PPBI是“乒乓BD指示器”，告诉你它使用了什么。



      以下为原文

    "Would it be correct to say that PPBRST forces SIE to use even BD's when set?"   Yes.  That is the way I interpret the datasheet.
 
"If cleared after being set, will SIE first use even and then odd BD's?"  Probably, but why do you care?  The USTAT register, which tells the firmware about the last transaction, includes the PPBI bit.  PPBI is "Ping Pong BD indicator" and tells you which it used.
 

丹诺，我会关心，因为我想知道如何武装端点，DATA0或DATA1。



      以下为原文

    Danno, I would care because I want to know how to arm the endpoints, DATA0 or DATA1.
 

我将启用这两个，让USB外围设备告诉我它使用了PPBI。



      以下为原文

    I would enable both and let the USB peripheral tell me which one it used via PPBI.