Cypress Semiconductor FX2LP Información técnica Pagina 78

  • Descarga
  • Añadir a mis manuales
  • Imprimir
  • Pagina
    / 460
  • Tabla de contenidos
  • MARCADORES
  • Valorado. / 5. Basado en revisión del cliente
Vista de pagina 77
EZ-USB FX2 Technical Reference Manual
Page 2-24 EZ-USB FX2 Technical Reference Manual v2.1
2.3.11 Firmware Load
The USB endpoint-zero protocol provides a mechanism for mixing vendor-specific requests with
standard device requests. Bits 6:5 of the bmRequestType field are set to 00 for a standard device
request and to 10 for a vendor request.
The FX2 responds to two endpoint-zero vendor requests, RAM Download and RAM Upload.
These requests are active whether RENUM=0 or RENUM=1.
Because bit 7 of the first byte of the SETUP packet specifies direction, only one bRequest value
(0xA0) is required for the upload and download requests. These RAM load commands are avail-
able to any USB device that uses the FX2 chip.
A host loader program will typically write 0x01 to the CPUCS register to put the FX2’s CPU into
RESET, load all or part of the FX2’s internal RAM with code, then reload the CPUCS register with
0 to take the CPU out of RESET.
Table 2-23. Firmware Download
Byte Field Value Meaning Firmware Response
0 bmRequestType
0x40
Vendor Request, OUT
None required.
1 bRequest
0xA0
“Firmware Load”
2 wValueL
AddrL
Starting address
3 wValueH
AddrH
4 wIndexL 0x00
5 wIndexH 0x00
6 wLengthL
LenL
Number of bytes
7 wLengthH LenH
Table 2-24. Firmware Upload
Byte Field Value Meaning Firmware Response
0 bmRequestType
0xC0
Vendor Request, IN
None Required.
1 bRequest
0xA0
“Firmware Load”
2 wValueL AddrL Starting address
3 wValueH
AddrH
4 wIndexL 0x00
5 wIndexH 0x00
6 wLengthL
LenL
Number of Bytes
7 wLengthH
LenH
Vista de pagina 77
1 2 ... 73 74 75 76 77 78 79 80 81 82 83 ... 459 460

Comentarios a estos manuales

Sin comentarios