Cypress Semiconductor SL811HS Bedienungsanleitung PDF herunterladen (Seite 28)

Cypress Semiconductor Corporation

SL811HS and SL811HST: Application Notes

and specifications contained in this document are subject to change without

notice.

Date: 07/26/01

Revision: 1.21

Page: 28

Example for doing PID_IN or PID_OUT or PID_SETUP with payload = 8;

then the Software requirement is:

static short low_speed_via_hub = 0;static short low_speed_via_hub = 0;

// the low_speed_via_hub will be set high only when the HUB // the low_speed_via_hub will be set high only when the HUB detect lowdetect low

// speed device attach to the HUB.// speed device attach to the HUB.

short int_cnt=0; short int_cnt=0;

short pl, Cmd=DATA0_RD, loop=30000; short pl, Cmd=DATA0_RD, loop=30000;

if (low_speed_via_hub) if (low_speed_via_hub)

{ {

pl = payload + 16; // low speed pl = payload + 16; // low speed

Cmd |= 0x80; // Cmd |= 0x80; //

} }

else pl = (payload>>3) + 3; else pl = (payload>>3) + 3;

SL11Write SL11Write(EP0Status, (BYTE)( (PID_IN << 4) + 0 ) );(EP0Status, (BYTE)( (PID_IN << 4) + 0 ) );

SL11Write(EP0Counter, 0); SL11Write(EP0Counter, 0);

SL11Write(EP0XferLen, payload); // setup 3 SL11Write(EP0XferLen, payload); // setup 3--byte header + payloadbyte header + payload

SL11Write(EP0Address, 0x10); // DATA0 SL11Write(EP0Address, 0x10); // DATA0

while( loop while( loop---- ) )

{ {

int_cnt++; int_cnt++;

SL11Write(IntStatus SL11Write(IntStatus,0xff);,0xff);

if (SL11Read(0xf) > (BYTE)pl) if (SL11Read(0xf) > (BYTE)pl)

SL11Write(EP0Control,Cmd); // Enable ARM SL11Write(EP0Control,Cmd); // Enable ARM

else else

SL11Write(EP0Control,Cmd|0x20); // Enable ARM and Wait after SOF SL11Write(EP0Control,Cmd|0x20); // Enable ARM and Wait after SOF

// just for example only. If CPU uses the Interrupt // just for example only. If CPU uses the Interrupt

Delay1ms(2,0); Delay1ms(2,0);

// should check the interrupt variable "int_cnt" // should check the interrupt variable "int_cnt"

if ((SL11Read(IntStatus)&1)==0) if ((SL11Read(IntStatus)&1)==0)

printf("Missing Interrupt printf("Missing Interrupt\\n");n");

else int_cnt else int_cnt----;;

} }

if (int_cnt) if (int_cnt)

printf("Missing interrupt printf("Missing interrupt\\n");n");

4.1.13 SOF or EOP Generation

The USB Specification v1.1 requires a host controller to generate an End of Packet (EOP) at

regular timed intervals - nominally every 1 millisecond - to keep low speed devices alive. An

EOP is defined as two single-ended zeros (SE0) followed by a J State. See figure below for

EOP pulse width.

Figure 5: EOP Pulse Width

1 2 ... 23 24 25 26 27 28 29 30 31 32 33 ... 42 43

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