AT89C5131A-M Atmel Corporation, AT89C5131A-M Datasheet - Page 128

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AT89C5131A-M

Manufacturer Part Number
AT89C5131A-M
Description
Manufacturer
Atmel Corporation
Datasheets

Specifications of AT89C5131A-M

Flash (kbytes)
32 Kbytes
Max. Operating Frequency
48 MHz
Cpu
8051-12C
Max I/o Pins
34
Usb Transceiver
1
Usb Speed
Full Speed
Usb Interface
Device
Spi
1
Twi (i2c)
1
Uart
1
Sram (kbytes)
1.25
Eeprom (bytes)
1024
Self Program Memory
API
Operating Voltage (vcc)
2.7 to 5.5
Timers
4
Isp
UART/USB
Watchdog
Yes
21.4.3
128
AT89C5130A/31A-M
Bulk/Interrupt IN Transactions in Standard Mode
A NAK handshake is sent by the USB controller only if the banks 0 and 1 has not been released
by the firmware.
If the Host sends more bytes than supported by the endpoint FIFO, the overflow data won’t be
stored, but the USB controller will consider that the packet is valid if the CRC is correct.
Figure 21-9. Bulk/Interrupt IN Transactions in Standard Mode
An endpoint will be first enabled and configured before being able to send Bulk or Interrupt
packets.
The firmware will fill the FIFO with the data to be sent and set the TXRDY bit in the UEPSTAX
register to allow the USB controller to send the data stored in FIFO at the next IN request con-
cerning this endpoint. To send a Zero Length Packet, the firmware will set the TXRDY bit without
writing any data into the endpoint FIFO.
Until the TXRDY bit has been set by the firmware, the USB controller will answer a NAK hand-
shake for each IN requests.
To cancel the sending of this packet, the firmware has to reset the TXRDY bit. The packet stored
in the endpoint FIFO is then cleared and a new packet can be written and sent.
When the IN packet has been sent and acknowledged by the Host, the TXCMPL bit in the UEP-
STAX register is set by the USB controller. This triggers a USB interrupt if enabled. The firmware
will clear the TXCMPL bit before filling the endpoint FIFO with new data.
The firmware will never write more bytes than supported by the endpoint FIFO.
All USB retry mechanisms are automatically managed by the USB controller.
IN
IN
HOST
ACK
DATA0 (n Bytes)
NAK
UFI
TXCMPL
Endpoint FIFO Write Byte 1
Endpoint FIFO Write Byte 1
Endpoint FIFO Write Byte 2
Endpoint FIFO Write Byte n
Clear TXCMPL
Set TXRDY
C51
4337K–USB–04/08

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