Table of Contents
1. USBFS MULTI EP PERFORMANCE
1.1. INTERRUPT TRANSFER USE SINGLE EP
OPERATING SYSTEM RATE LIMIT : 64KiB/s:
1000 / 1ms(bInterval) = 1000Hz 64(BYTE) * 1000Hz = 64KiB/s
1.2. INTERRUPT TRANSFER USE MULTI EP:
USB IF0 HID EP IN 0X81 USB IF1 HID EP IN 0X82 USB IF2 HID EP IN 0X83
IF YOUR USB DEVICE(MCU/SOC) IS FAST, CAN PROC ALL EP IN REQEUST IN TIME:
MAX RATE IS : 64KiB/s * 3 = 192KiB/s
USB HOST ------SOF-------> BORDCAST USB HOST ----EP 0x81 IN REQ---> USB DEVICE USB DEVICE ----ACK-------> USB HOST USB HOST ----EP 0x82 IN REQ---> USB DEVICE USB DEVICE ----ACK-------> USB HOST USB HOST ----EP 0x83 IN REQ---> USB DEVICE USB DEVICE ----ACK-------> USB HOST ............. USB HOST ------SOF-------> BORDCAST
IF YOUR USB DEVICE(MCU/SOC) IS TOO SLOW, CAN'T PROC SOME EP IN REQEUST IN TIME:
MAX RATE IS : 64KiB/s * 2 = 128KiB/s
USB HOST ------SOF-------> BORDCAST USB HOST ----EP 0x81 IN REQ---> USB DEVICE USB DEVICE ----ACK-------> USB HOST USB HOST ----EP 0x82 IN REQ---> USB DEVICE USB DEVICE ----NAK-------> USB HOST USB HOST ----EP 0x83 IN REQ---> USB DEVICE USB DEVICE ----ACK-------> USB HOST ............. USB HOST ------SOF-------> BORDCAST
WIRESHARK USBLL SNIFFER SAMPLE:
