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Add stepper sequencer documentation
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schlae committed Jun 12, 2024
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70 changes: 70 additions & 0 deletions README.md
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Expand Up @@ -145,6 +145,76 @@ Differential signals from the currently selected read/write head gets amplified

The preamp is similar to the NE592 video amplifier chip. See the datasheet for examples of different gain networks.

### 11782-501 "STEP SEQR"

The step sequencer generates the 5-phase signals that drive the stepper motor power driver chips.

**Pin Description**

| Pin | Name | Direction | Description |
|-----|-------|-----------|-------------------------------------------------|
| 13, 20 | VCC | Power In | 5V power rail. |
| 10, 19 | GND | Ground | Connect to ground. |
| 1 | MTA+ | Output | Motor phase A high drive |
| 2 | MTA- | Output | Motor phase A low drive |
| 4 | MTB+ | Output | Motor phase B high drive |
| 5 | MTB- | Output | Motor phase B low drive |
| 6 | MTC+ | Output | Motor phase C high drive |
| 7 | MTC- | Output | Motor phase C low drive |
| 8 | MTD+ | Output | Motor phase D high drive |
| 9 | MTD- | Output | Motor phase D low drive |
| 11 | MTE+ | Output | Motor phase E high drive |
| 12 | MTE- | Output | Motor phase E low drive |
| 14 | RESET# | Input | Active low reset input. Drive low to go to sequence 0. |
| 15 | CLK | Input | Clock input. Sequence changes on rising edge. |
| 3 | RETRACT# | Input | Active low retract input. Drive low to set all phase outputs low. |
| 17 | DIRECTION | Input | Direction pin. The sequence tables all assume this pin is high. |
| 16 | HALFSTEP# | Input | Active low half-step input. Activating this pin turns on half-step mode. |
| 18 | HALFSTEP2# | Input | Active low alternative half-step mode input. When asserted while HALFSTEP# is low, turns on alternate half-step mode. Ignored when HALFSTEP# is deasserted.|

**Detailed Description**

This device is basically a sequence controller chip that drives the phase signals going to the stepper motor driver chips.

They follow these phase tables.

For each phase, the states below correspond with the following output states. Phase 0 corresponds with the phase after a reset. When DIRECTION=0, proceed from phase 0, 1, 2...9 and wrap back to 0. When DIRECTION=1, proceed from phase 0, 9, 8, 7...1.

| Phase | + Pin State | - Pin State |
|-------|-------------|-------------|
| z | Low | Low |
| H | High | Low |
| L | Low | High |


Std: Standard step mode (HALFSTEP#=1, HALFSTEP2#=x, DIRECTION=0)

Half: Half step mode (HALFSTEP#=0, HALFSTEP2#=1, DIRECTION=0)

AltHalf: Alternate half step mode (HALFSTEP#=0, HALFSTEP2#=0, DIRECTION=0)

| Std | 0 | . | 1 | . | 2 | . | 3 | . | 4 | . | 5 | . | 6 | . | 7 | . | 8 | . | 9 | . |
|-------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| A | z | | L | | L | | L | | L | | z | | H | | H | | H | | H | |
| B | L | | z | | H | | H | | H | | H | | z | | L | | L | | L | |
| C | H | | H | | z | | L | | L | | L | | L | | z | | H | | H | |
| D | L | | L | | L | | z | | H | | H | | H | | H | | z | | L | |
| E | H | | H | | H | | H | | z | | L | | L | | L | | L | | z | |
| **Half** | **0** | **1** | **2** | **3** | **4** | **5** | **6** | **7** | **8** | **9** | **10**| **11**| **12**| **13**| **14**| **15**| **16**| **17**| **18**| **19**|
| A | z | z | L | L | L | L | L | L | L | z | z | z | H | H | H | H | H | H | H | z |
| B | L | z | z | z | H | H | H | H | H | H | H | z | z | z | L | L | L | L | L | L |
| C | H | H | H | z | z | z | L | L | L | L | L | L | L | z | z | z | H | H | H | H |
| D | L | L | L | L | L | z | z | z | H | H | H | H | H | H | H | z | z | z | L | L |
| E | H | H | H | H | H | H | H | z | z | z | L | L | L | L | L | L | L | z | z | z |
| **AltHalf** | **0** | **1** | **2** | **3** | **4** | **5** | **6** | **7** | **8** | **9** | **10**| **11**| **12**| **13**| **14**| **15**| **16**| **17**| **18**| **19**|
| A | z | L | L | L | L | L | L | L | L | L | z | H | H | H | H | H | H | H | H | H |
| B | L | L | z | H | H | H | H | H | H | H | H | H | z | L | L | L | L | L | L | L |
| C | H | H | H | H | z | L | L | L | L | L | L | L | L | L | z | H | H | H | H | H |
| D | L | L | L | L | L | L | z | L | H | H | H | H | H | H | H | H | z | L | L | L |
| E | H | H | H | H | H | H | H | H | z | L | L | L | L | L | L | L | L | L | z | H |



### 10223-502 "RETURN"

This device moves the heads to the landing zone when it detects a power loss.
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