DM240415 Microchip Technology, DM240415 Datasheet - Page 24

• Manufacturer Part Number: DM240415
• Description: Accessory Development Starter Kit For Android General Purpose
• Manufacturer: Microchip Technology
• Series: -r

Specifications of DM240415

• Processor To Be Evaluated: PIC24FJ256GB110-I/PT
• Processor Series: PIC24F
• Data Bus Width: 16 bit
• Interface Type: USB
• Operating Supply Voltage: 3.3 V
• Design Resources: PIC24F ADK Schematic
• Main Purpose: Reference Design, Tablet
• Embedded: Yes, MCU, 16-Bit
• Utilized Ic / Part: PIC24F
• Primary Attributes: Android OS, Development Platform for Accessories, Arduino Compatible
• Secondary Attributes: Royalty Free, No Fee Licensed Software Library
• Lead Free Status / Rohs Status: Details

Microchip's Accessory Framework for Android(tm)
4.2.6
Receiving data from the Android device is very similar to sending data. There are two functions that are used:
AndroidAppIsReadComplete (
The AndroidAppRead (
situation where the Android device is the USB peripheral, this will initiate an IN request on the bus. If the Android device
doesn't have any information it will respond with NAKs. One key thing to know about the read function is that the buffer
passed to the read function must always be able to receive at least one packets worth of USB data. For full-speed USB
devices this is 64 bytes.
The AndroidAppIsReadComplete (
The read request will terminate if a couple of conditions occur. The first is if the total number of bytes requested has been
read. The second is if a packet with less than the maximum packet length is received. This typically indicates that fewer
bytes than requested are available and that no more packets are immediately pending. While this is true for most cases, it
may not be true for every case. If the target application is one of those exceptions, keep in mind that you may have to call
the read function multiple times in order to receive a complete transmission from the applications perspective. Remember
from the Keeping the Stack Running (
keep the stack running. This means that you shouldn't loop on the AndroidAppIsReadComplete (
function. Instead use either a state machine or booleans to indicate what you need to do.
}
while(1)
{
Receiving Data
}
if((buttonsNeedUpdate == TRUE) && (writeInProgress == FALSE))
{
}
//Keep the stack running
USBTasks();
//Do some extra stuff here
if(readInProgress == FALSE)
{
if(AndroidAppIsWriteComplete(device_handle, &errorCode, &size) == TRUE)
{
}
response_packet.command = COMMAND_UPDATE_PUSHBUTTONS;
response_packet.data = pushButtonValues;
errorCode = AndroidAppWrite(device_handle,(BYTE*)&response_packet, 2);
if( errorCode != USB_SUCCESS )
{
}
else
{
}
errorCode = AndroidAppRead(device_handle,
//If the device is attached, then lets wait for a command from the application
writeInProgress = FALSE;
if(errorCode != USB_SUCCESS)
{
}
DEBUG_ERROR("Error trying to send button update");
buttonsNeedUpdate = FALSE;
writeInProgress = TRUE;
//Error
DEBUG_ERROR("Error trying to complete write");
see page 23)() function is used to start a read request from the Android device. In the
see page 21)() and AndroidAppRead (
see page 17) section that the USBTasks() function needs to be called in order to
see page 21)() function is used to determine if a read request was completed.
(BYTE*)&command_packet,
(DWORD)sizeof(ACCESSORY_APP_PACKET));
see page 23)().
see page 21)()
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