Datasheet

Figure 2. Endpoint configuration
4 Endpoint Buffer Configuration
Each endpoint needs a buffer to store the received data or data to be sent. This chapter describes the configuration of the USB
endpoint buffer.
4.1 Buffer Descriptor Table
To manage USB endpoint communications, USBFS implements a Buffer Descriptor Table (BDT) in system memory，as shown
in Figure 3 . The BDT resides on a 512 byte boundary in system memory and is pointed to by the BDT Page Registers. Every
endpoint direction requires two 8-byte Buffer Descriptor (BD) entries. Therefore, a system with 16 fully bidirectional endpoints
would require 512 bytes of system memory to implement the BDT. The two BD entries allow for an EVEN BD and ODD BD entry
for each endpoint direction. The contents stored in the BDT are shown in Table 2.
Table 2. Buffer descriptor format
31:26 25:16 15.8 7 6 5 4 3 2 1 0
RSVD
BC
(10 bits)
RSVD
OWN
DATA0/1
KEEP/ NINC/ DTS/ BDT_STA
LL/
0 0
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NXP Semiconductors
Endpoint Buffer Configuration
USB to Multi VCOM on K32L2 Series MCU, Rev. 0, November 2019
Application Note 4 / 25