USB 1.1 Protocolos compatibles

Sistemas embebidos

Universal Serial Bus 1.1

¿Qué es USB 1.1?

USB 1.1 (Universal Serial Bus 1.1) is the original widely-deployed USB specification, supporting Low Speed (1.5 Mbps) and Full Speed (12 Mbps) data transfer over a differential D+/D- signal pair. USB 1.1 devices are still manufactured and widely used — keyboards, mice, microcontrollers with built-in USB, HID devices, CDC serial adapters, and many industrial/medical devices use USB 1.1 Full Speed. The protocol includes device enumeration, descriptor exchange, control/bulk/interrupt/isochronous transfer types, and hub-managed bus topology. Engineers debugging USB 1.1 devices need to analyze enumeration sequences, decode SETUP/IN/OUT token packets, verify descriptor responses, and diagnose communication errors at the packet level.

USB 1.1 Referencia rápida

type Serial, differential
signals D+, D-
max Speed 12 Mbps (Full Speed)
voltage Range 3.3V
standard USB 1.1

Instrumentos Acute compatibles con USB 1.1

Soluciones recomendadas

Recomendado para decodificación

TB3016F

TB3016F

Con canales analógicos

MSO2116E

MSO2116E

Todos los productos compatibles

Decodificación de protocolo
Disparo por hardware
Emulador de protocolo

Serie LA4000

Serie TravelBus

Serie TravelLogic

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¿Cómo analizar USB 1.1 con instrumentos Acute

1

Conecte su analizador lógico Acute a las señales USB D+ y D-, ya sea directamente en el conector o en una placa de derivacion.

2

Conecte un cable de tierra a la referencia de tierra de la placa objetivo.

3

En el software Acute, seleccione el USB 1.1 protocol decoder y asigne D+ y D- a los canales de entrada correspondientes.

4

Configure los parametros esperados de speed mode (Low Speed or Full Speed).

5

Capture y visualice los USB transactions showing SETUP, IN, OUT, and SOF tokens, data packets, handshake (ACK/NAK/STALL), and device descriptor contents during enumeration.

Preguntas frecuentes

Que tasa de muestreo necesito para el análisis USB 1.1 ?
USB Full Speed (12 Mbps) uses NRZI encoding, so data transitions can occur at 12 MHz. Sample at a minimum of 48 MHz (4x the data rate) for reliable decoding. For USB Low Speed (1.5 Mbps), 12 MHz sampling is sufficient. Higher sample rates of 100 MHz or more provide better margin for handling signal quality variations on the D+/D- lines.
Por que mi dispositivo USB 1.1 falla en la enumeración?
USB enumeration failures are commonly caused by incorrect device descriptor responses, timing violations in the SETUP-DATA-STATUS transaction sequence, or electrical issues on the D+/D- lines. Capture the bus during device connection and decode the enumeration sequence. Look for the host's SETUP packet requesting the device descriptor, verify the device responds with valid descriptor data within the required timeout, and check for NAK or STALL handshake responses that indicate the device is not ready or rejecting the request.
Cuantos canales se necesitan para el análisis de USB 1.1 ?
USB 1.1 requires 2 channels for D+ and D-. The decoder uses both differential lines to determine the bus state (J, K, SE0, SE1) and NRZI data encoding. If you also want to monitor the VBUS power line or a USB reset/suspend signal, add 1-2 additional channels. Most USB 1.1 debugging requires only 2 channels.

Protocolos relacionados

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