Figure 182. Double-Buffering Operation Example - Holtek HT32F52342 User Manual

32-Bit Arm ® Cortex ® -M0+ MCU
HT32F52342/HT32F52352
IN Transaction
Buffer Accessed
by USB SIE
Buffer Accessed Endpoint 4
by MCU
1st Data packet
processed by MCU
[UDBTG, MDBTG]=[0,0]→[0,1]→[1,1]→[1,0]→[0,0]→[0,1]→[1,1]→[1,0]→[0,0]
OUT Transaction
Endpoint 4
Buffer Accessed
by USB SIE
1st Data packet
received from Host
Buffer Accessed
by MCU
[UDBTG, MDBTG]=[0,0]→[0,1]→[1,1]→[1,0]→[0,0]→[0,1]→[1,1]→[1,0]→[0,0]

Figure 182. Double-buffering Operation Example

Rev. 1.30
Buffer toggled by SIE hardware
Endpoint 4
Buf 0
1st Data packet
transmitted to Host
Buffer toggled by MCU software
Endpoint 4
Buf 0 Buf 1
2nd Data packet
processed by MCU
Buffer toggled by SIE hardware
Endpoint 4
Buf 0 Buf 1
2nd Data packet
received from Host
Endpoint 4
Buf 0
1st Data packet
processed by MCU
565 of 656
Endpoint 4
Endpoint 4
Buf 1 Buf 0
2nd Data packet
3rd Data packet
transmitted to Host
transmitted to Host
Endpoint 4 Endpoint 4
Buf 0 Buf 1
3rd Data packet
processed by MCU
Endpoint 4 Endpoint 4
Buf 0 Buf 1
3rd Data packet
received from Host
Buffer toggled by MCU software
Endpoint 4 Endpoint 4
Buf 1 Buf 0
2nd Data packet 3rd Data packet
processed by MCU processed by MCU
t
t
September 28, 2018