# What are value in 8-bit high registers of TDR if 8-bit low registers are written?

Level 5
Level 5

Hi,

At first, 16-bit data is transfered from 16-bit transmit data buffer on the RAM to TDR by using DMAC. Transfer width is 16-bit.

Next, 8-bit data is transfered from 8-bit transmit data buffer on the RAM to TDR by uing DMAC. Transfer width is 8-bit.

In this case, what values are in 8-bit high register(especially, D8)?

a)0
b)Indefinite value
c)datas written at first.

d)others

Best Regards,

Inoue

1 Solution

# Re: What are value in 8-bit high registers of TDR if 8-bit low registers are written?

Employee
Employee

Hi,

Please see the other thread, register access is only allowed as 16 or 32bit valueFor UART, can DMACB Transfer width be used both 16bit and 8bit ?

So both will be written at the same time.

regards,

Achim

# Re: What are value in 8-bit high registers of TDR if 8-bit low registers are written?

Employee
Employee

Hi,

Please see the other thread, register access is only allowed as 16 or 32bit valueFor UART, can DMACB Transfer width be used both 16bit and 8bit ?

So both will be written at the same time.

regards,

Achim