Cypress Semiconductor FX2LP Información técnica Pagina 89

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Chapter 3. Enumeration and ReNumeration™ Page 3-11
3.8 FX2 Vendor Request for Firmware Load
Prior to ReNumeration, the host downloads data into the FX2’s internal RAM. The host can access
two on-chip FX2 RAM spaces — Program / Data RAM at 0x0000-0x1FFF and Data RAM at
0xE000-0xE1FF — which it can download or upload whether the CPU is in reset or running: These
two RAM spaces may also be boot-loaded by a “C2” EEPROM connected to the I²C-compatible
bus. The host may also write to the CPUCS register to put the CPU in or out of reset.
Off-chip RAM (on the 128-pin FX2’s address/data bus) cannot be uploaded or downloaded by the
host via the “Firmware Load” vendor request.
The USB Specification provides for
vendor-specific requests
to be sent over endpoint zero. The
FX2 uses this feature to transfer data between the host and FX2 RAM. The FX2 automatically
responds to two “Firmware Load” requests, as shown in Tabl e3-7 and Table 3-8.
Table 3-7. Firmware Download
Byte Field Value Meaning
FX2
Response
0 bmRequest
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 wLenghtL
LenL
Number of Bytes
7 wLengthH
LenH
Table 3-8. Firmware Upload
Byte Field Value Meaning
FX2
Response
0 bmRequest
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
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