DM163010 Microchip Technology, DM163010 Datasheet - Page 24

• Manufacturer Part Number: DM163010
• Description: BOARD DEMO PICDEM USB
• Manufacturer: Microchip Technology

Specifications of DM163010

• Processor To Be Evaluated: PlC16C745/765
• Interface Type: USB
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

PICDEM™ USB User’s Guide
DS41174A-page 20
2.2.8
2.2.9
PS/2 Firmware
The PS/2 firmware is entirely interrupt driven. As mentioned before, an inter-
Table 2.3: PS/2 State Machine Status Report
Report Descriptor
The report descriptors used in the example code for both the keyboard and
2.2.9.1
0x05, 0x01
0x09, 0x06
0xA1, 0x01
0x05, 0x07
0x19, 0xE0
0x29, 0xE7
0x15, 0x00
0x25, 0x01
0x75, 0x01
0x95, 0x08
0x81, 0x02
rupt is generated when the START bit is received, at which time the firmware
will begin its receive routine. In addition to this interrupt, every 168 ms, a timer
overflow interrupts the normal program flow and implements one state of the
mouse/keyboard/cursor demonstration state machine. This state machine
handles sending bytes to and translating bytes received from the PS/2
device, automatically. These two interrupts essentially handle everything,
except for transferring the bytes via USB to the PC. In addition, it does all of
this work in the background while a developer’s code runs in the foreground.
The only operation that the developer’s program must implement is sending
keyboard or mouse data to the PC via USB. The developer needs only to be
concerned with the TYPE and eight BUFFER registers. BUFFER registers 0
to 7 are the registers where translated PS/2 device data gets placed. TYPE
contains the following status bits:
mouse were copied directly out of the HID Usage Tables . The HID Usage
Tables document is published by the USB Implementers Forum
(www.usb.org). Many other useful HID report descriptor examples can be
found in this document. The keyboard and mouse report descriptors are not
sent out at the same time that the PICmicro MCU is enumerated by the host.
Rather, the PICmicro MCU will only send the report descriptor that corre-
sponds to the device it has detected as being attached at that time.
TYPE bit Name
0
1
2
3
CONNECTED
MOUSE
KEYBOARD
DATA READY
Keyboard Descriptor
usage page (generic desktop)
usage (keyboard)
collection (application)
usage page (key codes)
usage minimum (224)
usage maximum (231)
logical minimum (0)
logical maximum (1)
report size (1)
report count (8)
input (data, variable, absolute)
Description
1 = device connected
1 = device connected is a mouse
1 = device connected is a keyboard
1 = data is ready; must be cleared by user
©
2001 Microchip Technology Inc.