Continued RN-42 tinkering

I was able to get the mouse HID profile working on the RN-42 module.

Highlights

• SH,0220 for mouse
• Use Serial.write(val) or Serial.write(buf,len) to send hexadecimal values, instead of characters that get converted to their hex values. To send HID reports, I need to directly send the hexcodes, instead of their string representations.
• Alright, I can send HID reports. Although it’s overkill for ASCII characters, you can send RAW keypress reports as 0xFD (start byte), 0x9 (size 9 of report), 0x1 (descriptor indicating keyboard), modifier byte (0x20 or 0x2 for shift/capitalize), 0x0, then 6 scan codes. Sending 0x0 directly via the “write” function makes Arduino bug out, so send it as bluetooth.write((byte)0); Sending 0x0 alone will disconnect the device.
• For mouse: sends changes in X and Y position, in either negative (left/down) or positive (right, up). For positive hexadecimal numbers, begins with 0-7. Negative hexadecimal numbers begin with 8-F. Or you can directly write nonzero decimal numbers. Are the units pixels? I have WASD working now.
• I was able to get this working with input NOT from serial, and instead from an input pin (digital or analog).
• I was also able to get a mouse click set up. Referenced the Adafruit HID library, which implements a mouse and keyboard with similar HID reporting. The button register order is left - 1; right - 2; middle - 4, corresponding to the 1st, 2nd, and 3rd bits.
• Looking at the mouse sensor’s data sheet, looks like we’ll have to use SPI (clock signal, MOSI, MISO) In addition, there is a MOTION pin (HIGH normally, LOW active when motion detected). MOSI is used to initiate read operations, telling the sensor which registers to write to the MISO pin.

Helpful Resources

• Arduino Forum question on Serial.write(val)
• Arduino Forum question on writing zero/0/0x0 to a character (serial/bluetooth) buffer
• Adafruit HID library
• ADNS-9800 mouse sensor datasheet

tags:   electronics  | project-ETextileMultimeter  |