PIC16C765 Microchip Technology Inc., PIC16C765 Datasheet - Page 71

• Manufacturer Part Number: PIC16C765
• Description: 8-bit Cmos Microcontrollers With Usb
• Manufacturer: Microchip Technology Inc.

REGISTER 10-13: BUFFER DESCRIPTOR ADDRESS LOW
10.6.1
Endpoint buffers are located in the Dual Port RAM
area. The starting location of an endpoint buffer is
determined by the Buffer Descriptor.
10.7
An on-chip integrated transceiver is included to drive
the D+/D- physical layer of the USB.
10.7.1
A 3.3V regulator provides the D+/D- drives with power,
as well as an external pin. This pin is intended to be
used to power a 1.5k
line to signal a low speed device, as specified by the
USB 1.1 Specification. A +20% 200nF capacitor is
required on V
TABLE 10-1:
V
D-
D+
Legend:
USB
2000 Microchip Technology Inc.
bit7
bit 7-0: BA<7:0>: Buffer Address
Note 1: This register should always contain a value between B8h-DFh.
R/W-X
BA7
ENDPOINT BUFFERS
Transceiver
REGULATOR
The base address of the buffer controlled by this endpoint. The upper order bit address (BA8) of the
9-bit address is assumed to be 1h. This value must point to a location within the dual port memory
space, Bank 3 (1B8h - 1DFh).
OD = open drain, ST = Schmitt Trigger
Name
USB
R/W-X
BA6
for regulator stability.
USB PORT FUNCTIONS
(BDndAL: 1A2h, 1A6h, 1AAh, 1AEh, 1B2h, 1B6h)
+5% pull-up resistor on the D-
R/W-X
BA5
Function
V
R/W-X
D+
D-
USB
BA4
R/W-X
Input
Type
USB
USB
BA3
—
Preliminary
Output
Power
R/W-X
Type
USB
USB
BA2
FIGURE 10-2: EXTERNAL CIRCUITRY
10.7.1.1
The V
current is sufficient for a pull-up only.
10.8
Microchip Technology provides a comprehensive set
of Chapter 9 Standard requests functions to aid devel-
opers in implementing their designs. See Microchip
Technology’s website for the latest version of the soft-
ware libraries.
Regulator Output Voltage
USB Differential Bus
USB Differential Bus
Note: The PIC16C745/765 requires an external resistor and
R/W-X
BA1
USB
PIC16C745/765
capacitor to communicate with a host over USB.
USB Software Libraries
provides a 3.3V nominal output. This drive
V
USB
V
R/W-X
PIC16C745/765
USB
APPLICATION
BA0
D+
D-
Output
bit0
Description
1.5K
R = Readable bit
W = Writable bit
U = Unimplemented bit,
-n = Value at POR reset
X = Don’t care
read as ‘0’
200 nF
DS41124C-page 71
Controller/HUB
Host