Serial Wombat
a general-purpose digital interface
device for hobbyists, engineers and students
Did you know...
Channel modes are at the heart of the Serial Wombat design. Every pin is assigned a channel mode, and this channel mode determines what the pin does. Some modes are very simple, and may simply set a pin high or low. Other channel modes are much more complex, and can do interesting things such as generating Morse Code, controlling a servo, or measuring, filtering, or averaging an Analog Input.
Every channel mode has a unique channel mode number. This number is used by the Configure Channel Mode commands to tell the Wombat what a pin is supposed to do. Many pins may use the same channel mode, and they will all work independently. This allows you to control more than one servo, measure more than one voltage, or monitor multiple rotary encoder knobs.
Available Channel Modes (modes without links have been coded and tested, but not yet documented):
| Mode: | Channel Mode Number (Decimal, Hex) |
Function: |
| Direct | 0, 0x00 | A function in direct mode is controlled by the Host. The host can command a pin to be high, low, or input |
| Controlled | 1, 0x01 | Some functions, such as reading a rotary encoder, require more than one pin. When one pin takes control of another pin, the controlled pin's channel mode is automatically set to Controlled. |
| Morse | 4, 0x04 | Generate Morse Code signals based on the data in a queue. |
| Hysteresis | 5, 0x05 | Control a pin based on the public data of another pin (an analog input, for example). This is the sort of control often used by thermostats. |
| Raw A/D | 6, 0x06 | Continuously measure a voltage input, and provide its value as public data. |
| A/D with first order filtering | 7, 0x07 | Continuously measure and low-pass filter a voltage input, and provide the result as public data. |
| Matrix Keypad Scanning | 8, 0x08 | Scan a matrix encoded keypad, and provide the key states, current pressed key, or last pressed key as public data. Optionally place keypresses or key transitions into a queue for retreival by the host. This mode takes control of other pins connected to the other rows and columns. |
| Watchdog | 9, 0x09 | The host periodically resets a timer. If the host ever allows the timer to expire, then a pin is pulsed for a period of time. This can be used to reset the host. |
| Diagnostics | 10, 0x0A | This pin monitors an input, and the state of another output pin. If the relationship between the pins is wrong, then the output pin is reconfigured to a safe, default state. This can be used to quickly shut off an output circuit which is short-circuited. |
| Rotary Encoder Input | 11, 0x0B | Monitor this pin and another to determine if a rotary encoder knob has been rotated. |
| Debouncing | 12,0x0C | Many switches "bounce" back and forth for a few milliseconds when they are pressed. A debouncing input will eliminate these false transitions. |
| Counter | 13,0x0D | A pin in this mode can count input transitions. A counter can be incremented on rising, falling, or both edges. Some pins have hardware support to allow very frequent transitions to be counted. The other pins require that the events to be counted occur slower than the frame rate. |
| A/D with averaging | 15,0x0F | Continuously measure a voltage input, and average the results to reduce noise. |
| Pulse | 16, 0x10 | Pulse an output for a configurable amount of time when some public data changes. This is useful for blinking a user-feedback LED or piezo buzzer in response to a keypad or rotary encoder change. It can also be used with the received-data counter public data to blink an LED whenever the host communicates with the Wombat. |
| Servo Control | 17, 0x11 | Control a servo motor based on commands from the host or public data from another pin. |
| Analog Direct | 18, 0x12 | Generate a PWM output or drive an off-board D/A or digital potentiometer based on a duty cycle configured by the host. Some pins have hardware support allowing high-frequency PWM generation. The other pins implement PWM in software, allowing the user to choose the trade-off between frequency and resolution. The user can reconfigure a pin to be the chip-select for an external A/D or digital potentiometer using the Hardware Mode command. |
| Analog Follow | 19,0x13 | Generate a PWM output or drive an off-board D/A or digital Pot based on some public data. This allows a pin's output to be controlled by the public data provided by some other pin function. |
| Unipolar Stepper Motor | 23, 0x17 | Use four of the Wombat's pins to spin or position a Unipolar Stepper Motor |
| Hardware Pulse Measurement | 24, 0x18 | Using special hardware available on certain pins, the Serial Wombat can measure very rapid transitions. |
| 2D Lookup Table | 25, 0x19 | Transform the data provided by a pin using a table of points which you provide. Then output the result as a PWM, or provide the result to another pin |
| SPI Master | 26, 0x1A | Control a SPI device using the Wombat's hardware SPI capability |
| HD44780
LCD controller |
27, 0x1B | Control any HD44780 based LCD display |
| Remote | 30, 0x1E | Read and decode key presses from Sony Compatible remote controls |
| DataLogger | 31, 0x1F | Store the public data from up to 4 pins into a queue at regular intervals |
| Min/Max | 32,0x20 | Keep track of a pin's minimum and maximum public data or A/D value |
| LCD Controller | 241,0xF1 | Control a WD-C2401 LCD Panel (in add on package) |
| LCD Controller 2 | 242,0xF2 | Control a 24 x 2 Line HD44780 based LCD Panel (in add on package) |