Z8523L08VEG Datasheet, PDF (29/118 Pages) Zilog, Inc. – Enhanced Serial Communications Controller

Z80230/Z85230/L
Product Specification
24
1. WR15 bit 0 must be reset to 0 to address the SYNC character in register WR7. If bit 6 of
WR7’ is set to 1, then WR7’ can be read by performing a read cycle to RR14. The WR7’
features remain enabled until specifically disabled or by a hardware or software reset. Bit
5 is set to 1 and all other bits are reset to 0 after a reset.
For applications which use either the Zilog Z8X30SCC or Z80230, these two device types
can be identified in software with the following test:
1. Write 01H to Write Register 15
2. Read Register 15
If bit 0 is set to 0, the device is Z8X30SCC. If bit 0 is set to 1, it is a Z80C30. If the device
is Z8XC30, a write to WR15 is required before proceeding. If the device is Z80230, all
writes to address 7 are to WR7’ until WR15 is set to 0.
The WR7 register bits are described below:
Bit 7 (Not used)
This bit must always be 0.
Bit 6 (Extended Read Enable)
Setting this bit to 1 enables WR3, WR4, WR5, WR7’ and WR10 to be read by issuing a
READ command for RR9 (WR3) RR4, RR5, RR14 (WR7’) and RR11 (WR10), respec-
tively.
Bit 5 (Transmit FIFO Interrupt Level)
If this bit is set to 1, the TBE interrupt is generated when the transmit FIFO is completely
empty. If this bit is set to 0, the TBE interrupt is generated when the top byte of the trans-
mit FIFO is empty. This bit is set following a hardware or channel reset.
In DMA REQUEST ON TRANSMIT mode, when using either the W/REQ or DTR/REQ
pins, the request is asserted when the Tx FIFO is completely empty if WR7’ bit 5 is set to
1. The request is asserted when the top byte of the FIFO is empty if bit 5 is reset.
Bit 4 (DTR/REQ Timing)
If this bit is set to 1 and the DTR/REQ pin is used for REQUEST mode (WR14 bit 2 is 1),
the deactivation of the DTR/REQ pin is identical to the W/REQ pin as displayed in
Figure 12 on page 25. If this bit is reset, the deactivation time is 4TcPc.
PS005308-0609
Z80230/Z85230/L Enhancements