NEC mPD78F0730 Preliminary User's Manual page 324

(3) UF0 EP0 setup register (UF0E0ST)
The UF0E0ST register holds the SETUP data sent from the host.
This register is read-only, in 8-bit units. A write access to this register is ignored.
The UF0E0ST register always writes data when a SETUP transaction has been received. The hardware sets
the PROT bit of the UF0IS1 register when it has correctly received the SETUP transaction. It sets the
CPUDEC bit of the UF0IS1 register in the case of an FW-processed request. Then an interrupt request
(INTUSB0B) is issued. In the case of an FW-processed request, be sure to read the request in 8-byte units. If
it is not read in 8-byte units, the subsequent requests cannot be correctly decoded. The read counter of the
UF0E0ST register is not cleared even when Bus Reset is received. Always read this counter in 8-byte units
regardless of whether Bus Reset is received or not.
Because the UF0E0ST register always enables writing, the hardware overwrites data to this register even if a
SETUP transaction is received while the data of the register is being read. Even if the SETUP transaction
cannot be correctly received, the CPUDEC interrupt request and Protect interrupt request are not generated,
but the previous data is discarded. If a SETUP token of less than 8 bytes is received, however, the received
SETUP token is discarded, and the previously received SETUP data is retained. If the SETUP token is
received more than once when control transfer is executed once, be sure to check the PROT bit of the UF0IS1
register under the conditions below. If PROT bit = 1, read the UF0E0ST register again because the SETUP
transaction has been received more than once.
<1> If a request is decoded by FW and the UF0E0R register is read or the UF0E0W register is written
<2> When preparing for a STALL response for the request to which the decode result does not correspond
Caution Be sure to read all the stored data. The UF0E0ST register is always updated by the request in
UF0E0ST E0S7
Bit position
7 to 0
The operation of the UF0E0ST register is illustrated below.
324
Downloaded from Elcodis.com electronic components distributor
CHAPTER 12 USB FUNCTION CONTROLLER (USBF)
the SETUP transaction.
7 6 4
5
E0S6 E0S5 E0S4
Bit name
E0S7 to E0S0 These bits hold the SETUP data sent from the host.
Preliminary User's Manual U19014EJ1V0UD
3 2 1
E0S3 E0S2 E0S1 E0S0
Function
0
Address After reset
FF18H 00H