r4f2426 Renesas Electronics Corporation., r4f2426 Datasheet - Page 1041

• Manufacturer Part Number: r4f2426
• Description: 16-bit Single-chip Microcomputer H8s Family / H8s/2400 Series
• Manufacturer: Renesas Electronics Corporation.

19.3.8
SSRDR is an 8-bit register that stores receive data. When 8-bit data length is selected by bits
DATS1 and DATS0 in SSCRL, SSRDR0 is valid. When 16-bit data length is selected, SSRDR0
and SSRDR1 are valid. When 24-bit data length is selected, SSRDR0, SSRDR1, and SSRDR2 are
valid. When 32-bit data length is selected, SSRDR0 to SSRDR3 are valid. Be sure not to access to
invalid SSRDR.
When the SSU has received 1-byte data, it transfers the received serial data from SSTRSR to
SSRDR where it is stored. After this, SSTRSR is ready for reception. Since SSTRSR and SSRDR
function as a double buffer in this way, consecutive receive operations can be performed.
Read SSRDR after confirming that the RDRF bit in SSSR is set to 1.
SSRDR is a read-only register, therefore, cannot be written to by the CPU.
Table 19.3 Correspondence Between DATS Bit Setting and SSRDR
19.3.9
SSTRSR is a shift register that transmits and receives serial data.
When data is transferred from SSTDR to SSTRSR, bit 0 of transmit data is bit 0 in the SSTDR
contents (MLS = 0: LSB first communication) and is bit 7 in the SSTDR contents (MLS = 1: MSB
first communication). The SSU transfers data from the LSB (bit 0) in SSTRSR to the SSO pin to
perform serial data transmission.
In reception, the SSU sets serial data that has been input via the SSI pin in SSTRSR from the LSB
(bit 0). When 1-byte data has been received, the SSTRSR contents are automatically transferred to
SSRDR. SSTRSR cannot be directly accessed by the CPU.
SSRDR
0
1
2
3
SS Receive Data Registers 0 to 3 (SSRDR0 to SSRDR3)
SS Shift Register (SSTRSR)
00
Valid
Invalid
Invalid
Invalid
01
Valid
Valid
Invalid
Invalid
DATS[1:0] (SSCRL[1:0])
Section 19 Synchronous Serial Communication Unit (SSU)
10
Valid
Valid
Valid
Valid
Rev. 1.00 Sep. 19, 2008 Page 1013 of 1270
11 (Setting Invalid)
Valid
Valid
Valid
Invalid
REJ09B0466-0100