FMC Host Digital IO Device¶
- Authors
Jonathan P. Newman
- IO
Frame Source, Frame Sink, Register Access
- ONIX ID
18
- ONIX Hubs
Description¶
The FMC Host Digital IO device sends and receives digital data to and from Breakout Board and allows control over its display state. This includes:
8x 5-volt tolerate digital inputs sampled at 10 MHz
8x digital outputs sampled at 10 MHz
HARP bus controller
6x user buttons
LED brightness and on/off state
Digital communication with the Breakout Board occurs using a simple serialization protocol.
Breakout to Host Serialization¶
The breakout to host serialization protocol is as follows:
- Buttons
Buttons press state. Each bit represents the press state of a single button in the 6-buttons bank.
0: Up
1: Down
- Digital In
Digital input port. Each bit represents state of a signal line in the 8-bit port.
0: Low
1: High
- Pnn
Headstage port power state. Each bit represents the power state of one of the four headstage ports.
0: Power off
1: Power on
A clock recovery circuit is required at the receiver to generate clk from
sclk in order to sample the dat lines.
Host to Breakout Serialization¶
The host to breakout serialization protocol is as follows:
- CMD
Two bit command word that determines what to do with SW.
0b00: Shift slow bits into slow shift register
0b01: Validate and move slow shift register to outputs and set initial state to [0, …, 0, slow1, slow0]. slow1 should be the desired MSB at next command.
0b10: Reserved, same as 0b00 currently. Don’t use.
0b11: Reset
- SW
Two-bit “slow-word” part. These bits are accumulated over time in order to control the display state and non-timing critical apsects of the breakout board. For instance, LED colors and brightness, headstage lock state, etc. As of this writing, for Breakout Board, a complete slow-word is as follows.
which are defined as follows:
Acq. Running: Host hardware run state. 0 = not running, 1 = running
Acq. Reset Done: Host reset state. 0 = reset not complete, 1 = reset complete
Reserved: NA
LED Level: 4 bit register for general LED brighness. 0 = dimmest, 16 = brightest
LED Mode: 2 bit register for LED mode. 0 = all off, 1 = only power/running, 2 = power/running, pll, harp, 3 = all on
Port X Status: 2 bit register describing the headstage port state. 00: power off, 01: power on, 10: locked, 11: device map good.
Analog IO Dir.: 12 bit register describing the direcitonality of each of the analog inputs. 0 = input, 1 = output.
HARP Config.: 2 bit register for possible future harp configuration.
GPIO Dir.: 16 bit register for possible future digital io directionality configuration.
- Digital Out
Digital output port state. Each bit represents state of an output signal line in the 8-bit port.
0: Low
1: High
A clock recovery circuit is required at the receiver to generate clk from
sclk in order to sample the dat line.
Register Programming¶
Address |
Name |
Access |
Time of Effect |
POR Value |
Reset Action |
Description |
|---|---|---|---|---|---|---|
0x00 |
ENABLE |
R/W |
On Reset |
Implementation dependent, see hub documentation |
None |
The LSB is used to enable or disable the device data stream:
|
0x01 |
LEDMODE |
R/W |
Immediate |
0x0003 |
None |
The two LSBs determine the breakout board’s LED display mode:
|
0x02 |
LEDLVL |
R/W |
On Reset |
0x0007 |
None |
The four LSBs dertermine the overall LED brightness. Brightness increases linearly with this register’s 0-15 value. |
0x03 |
HARPCONF |
R/W |
On Reset |
0x0000 |
None |
HARP Bus configuration. Reserved for future use. |
0x04 |
GPIODIR |
R/W |
On Reset |
0x0000 |
None |
GPIO configuraiton. Reserved for future use. |
Device To Host Data Frames¶
Each frame transmitted to the host consists of a single data specifying the current digital input and user input state.
Note
Input frames are only transmitted if there is a change in digital input or user input state.
- Input Port State
8-bit input port state
- Link State
On/off state of each headstage link.
- Button State
Press state of each button.
Host To Device Data Frames¶
Each frame sent to the device contains an 8-bit word specifying the digital output port state:
- Output Port State
8-bit output port state