GD32F20x User Manual
624
Note:
The data timeout programmed in the data timer register (SDIO_DATATO).
DS_WaitR
Wait for the start bit of the receive data.
1.Data receive ended
→
DS_Idle
2.DSM disabled
→
DS_Idle
3.Data timeout reached
→
DS_Idle
4.Receives a start bit before timeout
→
DS_Receive
Note:
The data timeout programmed in the data timer register (SDIO_DATATO).
DS_Receive
Receive data from the card and write it to the data FIFO.
1.Data block received
→
DS_WaitR
2.Data transfer ended
→
DS_WaitR
3.Data FIFO overrun error occurs
→
DS_Idle
4.Data received and Read Wait Started and SD I/O
mode enabled
→
DS_Readwait
5.DSM disabled or CRC fails
→
DS_Idle
DS_Readwait
Wait for the read wait stop command.
1.ReadWait stop enabled
→
DS_WaitR
2.DSM disabled
→
DS_Idle
24.4.2.
AHB interface
The AHB interface implements access to SDIO registers, data FIFO and generates interrupt
and DMA request. It includes a data FIFO unit, registers unit, and the interrupt / DMA logic.
The interrupt logic generates interrupt when at least one of the selected status flags is high.
An interrupt enable register is provided to allow the logic to generate a corresponding interrupt.
The DMA interface provides a method for fast data transfers between the SDIO data FIFO
and memory. The following example describes how to implement this method:
1. Complete the card identification process
2. Increase the SDIO_CLK frequency
3. Send CMD7 to select the card and configure the bus width
4. Configure the DMA1 as follows:
Enable DMA1 controller and clear any pending interrupts. Configure the DMA1_Channel3
source address register with the memory base address and DMA1_Channel3 destination
address register with the SDIO_FIFO register address. Program DMA1_Channel3 control
register (memory increment, not peripheral increment, peripheral and source width is word
size, M2M disable).
Summary of Contents for GD32F20 Series
Page 191: ...GD32F20x User Manual 191 Bits Fields Descriptions 31 0 TRNDATA 31 0 32 Bit Random data ...
Page 290: ...GD32F20x User Manual 290 conversion is ongoing ...
Page 325: ...GD32F20x User Manual 325 15 0 ALRM 15 0 RTC alarm value low ...
Page 385: ...GD32F20x User Manual 385 ...
Page 523: ...GD32F20x User Manual 523 clears AERR bit by writing 0 to it ...