8-14
IIC
Bits 4 and 5 are read-only.
8.4.13 Direct Control Register
This register is used for error recovery when a malfunction is detected on the IIC interface.
Bits 4:7 are set to ‘1’ by a hard reset. Soft reset does not affect this register. The soft reset bit should be set
to a 1 when using this register. This ensures that the IIC interface is held in the reset state while the
IIC_SCL and IIC_SDA outputs are being directly controlled via bits 2:3.
Bits 4 and 5 can be written to for direct control of the SDA and SCL lines. Bits 6 and 7 are used to verify
that the write occurred successfully and that the SDA and SCL lines can be controlled. If bits 6 and 7 do
not correspond to bits 4 and 5 respectively then the SCL line should be toggled repeatedly to regain con-
trol.
Table 94. Extended Control and Slave Status Register
Register ‘FF6X_000F’ - Extended Control and Slave Status
bit 0
Slave read complete. When set to a logic 1, a not acknowledge and/or a STOP condition was
received over the IIC bus. It is also set to a logic 1, when a repeated START condition is
received over the IIC bus, thus ending the read operation. A check should be done to see that
the slave data buffer was emptied by the read operation. The bit is not set when enable hold
SCL is set to a logic 0, the slave data buffer is empty and a read operation is received over the
IIC bus. In this case, the slave read needs service bit is set to a logic 1.
bit 1
Slave read needs service. When set to a logic 1, a request for data was received over the IIC
bus and the IIC macro had no data in the slave data buffer. It is also set to a logic 1 when the
slave data buffer goes empty during a slave read and more data is requested by the master. In
the first case, when enable hold SCL is also set to a logic 1, then the IIC bus is being held busy
until slave read needs service is cleared to a logic 0. Also, in this first case, if enable hold SCL is
set to a logic 0, then a not acknowledge is sent to end the current transfer and potentially free
the IIC bus. In the second case, SCL is held at a logic 0 regardless of the value of enable hold
SCL.
bit 2
Slave write complete. When set to a logic 1, a STOP signal has been received during a slave
write operation. It is also set to a logic 1 when a repeated START signal is received, thus ending
a slave write operation.
bit 3
Slave write needs service. Set to a logic 1 when the slave data buffer goes full during a slave
write. In this case, if enable hold SCL is also set to a logic 1, then the IIC bus is being held busy
until slave write needs service is cleared to a logic 0. If enable hold SCL is set to a logic 0, then
a not acknowledge was sent to end the current transfer and potentially free the IIC bus.
bit 4
Slave data buffer has data. When set to a logic 1, the slave data buffer has data in it. When
equal to a logic 0 the buffer is empty. This is a read-only bit.
bit 5
Slave data buffer full. When set to a logic 1, the slave data buffer is full. When equal to logic 0,
the slave data buffer is not full. This is a read-only bit.
bit 6
Enable pulsed IRQ. When set to a logic 1, the IIC_IRQ signal to the CPC700 interrupt controller
goes active for one clock period. When set to a logic 0, the IIC_IRQ signal stays active until the
IRQ active bit, bit 1 of the status register is cleared.
bit 7
Soft reset. When set to a logic 1, the IIC interface is reset. This reset is equivalent in function to
a hard reset or an IIC reset via the CPRRESET register with one exception. This bit is not
affected by the soft reset. It will remain a logic 1 until this bit is set to a logic 0, a hard reset
occurs, or an IIC reset via the CPRRESET register is asserted to a logic 1. Note that the
interface’s reset will remain active while this bit is set to a logic 1.
Содержание CPC700
Страница 1: ...CPC700 Memory Controller and PCI Bridge User s Manual Version 1 1 Issue Date 3 22 00 Preliminary...
Страница 10: ...Table of Contents x Table of Contents...
Страница 16: ...Tables xvi List of Tables...
Страница 28: ...1 12 CPC700 User s Manual Preliminary...
Страница 72: ...3 36 Processor Interface...
Страница 132: ...4 60 Memory Controller...
Страница 184: ...5 52 PCI Interface...
Страница 194: ...6 10 Clock Power Management and Reset...
Страница 224: ...8 18 IIC...
Страница 244: ...10 10 Interrupt Controller...
Страница 246: ...I 11 2 JTAG...
Страница 250: ...12 4 Processor Local Bus PLB...
Страница 262: ...14 10 Register Summary...
Страница 267: ...CPC700 User s Manual Preliminary...