Ultra Fast USB 2.0
7.5.2.1RESET_N for EEPROM Configuration
Hardware | Device | 8051 Sets | Attach |
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USB Reset | Idle | completion | |||||
reset | Recovery/ | Configuration | USB | ||||
recovery | request | ||||||
asserted | Stabilization | Registers | Upstream |
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| t1 |
| t4 | t5 | t6 |
| t7 |
| t2 | t3 |
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| RESET_N |
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| Figure 7.1 Reset_N Timing for EEPROM Mode |
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| Table 7.7 Reset_N Timing for EEPROM Mode |
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NAME | DESCRIPTION |
| MIN | TYP | MAX | UNITS | |
t1 | RESET_N asserted. |
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| 1 |
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| μsec |
t2 | Device recovery/stabilization. |
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| 500 | μsec | |
t3 | 8051 programs device configuration |
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| 20 | 50 | msec | |
t4 | USB attach (See Note). |
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| 100 | msec | |
t5 | Host acknowledges attach and signals USB reset. | 100 |
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| msec | ||
t6 | USB idle. |
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| Undefined |
| msec | |
t7 | Completion time for requests (with or without data |
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| 5 | msec | ||
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Note: All power supplies must have reached the operating levels mandated in Chapter 9, DC Parameters, prior to (or coincident with) the assertion of RESET_N.
7.5.3USB Bus ResetIn response to the upstream port signaling a reset to the device, the device does the following:
Note: The device does not propagate the upstream USB reset to downstream devices.
1.Sets default address to 0.
2.Sets configuration to: Unconfigured.
3.Negates PRTCTL[3:2] to all downstream ports.
4.Clears all TT buffers.
5.Moves device from suspended to active (if suspended).
6.Complies with Section 11.10 of the USB 2.0 Specification for behavior after completion of the reset sequence.
The host then configures the device and the device’s downstream port devices in accordance with the USB Specification.
SMSC USB2640/USB2641 | 49 | Revision 2.0 |
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