DLP-245PB DLP Design Inc, DLP-245PB Datasheet - Page 6

• Manufacturer Part Number: DLP-245PB
• Description: Interface Modules & Development Tools USB/Micro Dev Board
• Manufacturer: DLP Design Inc

Specifications of DLP-245PB

• Interface Type: USB
• Data Bus Width: 8 bit
• Operating Supply Voltage: 5.25 V
• Product: Interface Modules
• For Use With/related Products: 16F877A
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

TOKEN I/O
The 16F877A microcontroller on the DLP-245PB-G is shipped from the factory preprogrammed
with firmware that provides rudimentary access to the port pins via either the VCP or DLL drivers.
Features include the ability to read and write individual port pins as well as 8-bit port reads and
writes.
The firmware in the DLP-245PB-G also provides access to the 16F877A’s A/D converter,
EEPROM memory, and communications with digital temperature-sensing devices.
Commands sent to the Token I/O firmware must adhere to a specific communications protocol.
Each command sequence contains the following information:
The checksum is computed by exclusive-OR-ing every byte in the string. If the same checksum
is calculated by the 16F877A upon receipt of the packet, then a single-byte reply of 0x55 is
returned to the host. In the event of a checksum error, the 16F877A will return an error code of
0xAA. For example, setting port PIN_A1 high would require the following string of bytes:
0x03, 0xA6, 0x29, 0x01, 0x8D
Definition of the Bytes:
0x03 – Number of bytes in command (checksum excluded)
0xA6 – Command for set port pin high/low
0x29 – Affected port pin
0x01 – Desired state of port pin
0x8D – Checksum of previous 4 bytes
The port pins equate to hexadecimal numeric constants as defined here:
PORT A:
PIN_A0 0x28, PIN_A1 0x29, PIN_A2 0x2A,
PIN_A3 0x2B, PIN_A4 0x2C, PIN_A5 0x2D
V2.3
Byte 0:
Byte 1:
Byte 2…n-1:
Byte n:
Number of bytes in command sequence
Command
Parameter/Data bytes
Checksum
Page 6 of
15
February 2007