all the samples have been acquired.
Because the MCP3001 is a serial successive
approximation converter, the conversion can be halted
before reaching 10 bits. Because the ROBOEAR has eight-bit RAM, it routinely uses eight-bit conversions; 10-bit
conversions are available but must be analyzed externally.
Three electret microphones connect to the ROBOEAR
at connectors J10, J20, and J30. The connecting wires must
be long enough to arrange the microphones in the required
pattern. The microphones need to be arranged in the correct
order, in the form of an equilateral triangle 10 centimeters
on a side. This can also be thought of as mounting them
120 degrees apart on a circle with a radius of 5. 7 cm.
The order of the microphones (numbered according
to the analog channel to which they are wired) is critical
to determining the direction to a sound source. Figure 4
shows how the detected direction corresponds to this proper
arrangement. The plane of the microphones should be
parallel to the ground.
When the ROBOEAR is powered up, it reads jumper
J6 to determine whether to communicate with the host via
UART or SPI. The ROBOEAR boots up in “human” mode and
displays the menu that follows.
In human mode, when the host sends a command the
ROBOEAR echoes the command. If the command is not
valid, then a NAK is returned and the menu is sent again. If
the command is valid, an ACK is returned, the command is
executed, and the menu is sent again.
ROBOEAR, firmware 1.06
[E] Acquire one set of 8-bit data
[T] Acquire one set of 10-bit data
[R] Send raw data in CSV format
[P] Acquire and process one set of 8-bit data
[S] Send processing statistics
[B] Send bearing angles
[M] Set minimum channel range
[H] Use Hex values for raw data
[D] Use Decimal values for raw data
[A] Use BAM format for bearings
[G] Use decimal degrees format for bearings
[C] Computer control mode, ESCape to exit
If the host is controlling the ROBOEAR without human
intervention, it can put the ROBOEAR in “computer control”
mode by waiting until it sees a “?” then sending a “C” to the
Schematic 3. ROBOEAR analog input channels.
46 SERVO 09/10.2018