ST7260E1 STMicroelectronics, ST7260E1 Datasheet - Page 75

• Manufacturer Part Number: ST7260E1
• Description: LOW SPEED USB 8-BIT MCU FAMILY WITH UP TO 8K FLASH/ROM AND SERIAL COMMUNICATION INTERFACE (SCI)
• Manufacturer: STMicroelectronics

Specifications of ST7260E1

• 4 Or 8 Kbytes Program Memory: high density Flash (HDFlash), or FastROM with readout and write protection

ST7260xx
Note:
Procedure
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Clearing the TDRE bit is always performed by the following software sequence:
1.
2.
The TDRE bit is set by hardware and it indicates:
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This flag generates an interrupt if the TIE bit is set and the I bit is cleared in the CCR
register.
When a transmission is taking place, a write instruction to the SCIDR register stores the
data in the TDR register and which is copied in the shift register at the end of the current
transmission.
When no transmission is taking place, a write instruction to the SCIDR register places the
data directly in the shift register, the data transmission starts, and the TDRE bit is
immediately set.
When a frame transmission is complete (after the stop bit or after the break frame) the TC
bit is set and an interrupt is generated if the TCIE is set and the I bit is cleared in the CCR
register.
Clearing the TC bit is performed by the following software sequence:
1.
2.
The TDRE and TC bits are cleared by the same software sequence.
Break characters
Setting the SBK bit loads the shift register with a break character. The break frame length
depends on the M bit (see
As long as the SBK bit is set, the SCI send break frames to the TDO pin. After clearing this
bit by software the SCI insert a logic 1 bit at the end of the last break frame to guarantee the
recognition of the start bit of the next frame.
Idle characters
Setting the TE bit drives the SCI to send an idle frame before the first data frame.
Clearing and then setting the TE bit during a transmission sends an idle frame after the
current word.
Select the M bit to define the word length.
Select the desired baud rate using the SCIBRR and the SCIETPR registers.
Set the TE bit to assign the TDO pin to the alternate function and to send a idle frame
as first transmission.
Access the SCISR register and write the data to send in the SCIDR register (this
sequence clears the TDRE bit). Repeat this sequence for each data to be transmitted.
An access to the SCISR register
A write to the SCIDR register
The TDR register is empty.
The data transfer is beginning.
The next data can be written in the SCIDR register without overwriting the previous
data.
An access to the SCISR register
A write to the SCIDR register
Figure
39).
Serial communications interface (SCI)
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