ST92124V1Q-Auto STMicroelectronics, ST92124V1Q-Auto Datasheet - Page 301

• Manufacturer Part Number: ST92124V1Q-Auto
• Description: 8-bit MCU for automotive
• Manufacturer: STMicroelectronics

Specifications of ST92124V1Q-Auto

• Internal Memory: Single Voltage FLASH up to 256 Kbytes, RAM up to 8Kbytes, 1K byte E3 TM (Emulated EEPROM)
• Minimum Instruction Time: 83 ns (24 MHz int. clock)

J1850 BYTE LEVEL PROTOCOL DECODER (Cont’d)
10.9.6.3 DMA Management in Reception Mode
The DMA in reception is performed when the
RDRF bit of the STATUS register is set (by hard-
ware). The RDRF bit is reset as soon as the DMA
cycle is finished.
To enable the DMA feature, the RXD_M bit of the
IMR register must be set (by software).
Each DMA request performs the transfer of a sin-
gle byte from the RXDATA register of the peripher-
al toward Register File or Memory Space
139).
Each DMA transfer consists of three operations
that are performed with minimum use of CPU time:
– A load from the JBLPD data register (RXDATA)
Figure 139. DMA in Reception Mode
to a location of Register File/Memory addressed
JBLPD peripheral
RXDATA
(Figure
ST92124xxx-Auto/150xxxxx-Auto/250xxxx-Auto
– A post-increment of the DMA Address Register
– A post-decrement of the DMA transaction coun-
Note: When the REOBP pending bit is set (at the
end of the last DMA transfer), the reception DMA
enable bit (RXD_M) is automatically reset by hard-
ware. However, the DMA can be disabled by soft-
ware resetting the RXD_M bit.
Note: The DMA request acknowledge could de-
pend on the priority level stored in the PRLR regis-
ter.
through the DMA Address Register (or Register
pair);
(or Register pair);
ter, which contains the number of transactions
that have still to be performed.
Data received
Previous data
Memory space
Register File
Current
Address
Pointer
or
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