GMS30C7201 Datasheet, PDF (291/352 Pages) Hynix Semiconductor – 60MHz operation frequency Low power consumption

Slow AMBA Peripherals
Communication Procedure
The modem codec (GM0815) can receive normal data or codec control data with an nCON pin.
Procedures 1–3 below are for sending codec control data to GM0815. If there is no control data,
procedures 1 to 3 are not necessary.
Procedures 4 to 8 are for sending/receiving normal data to/from GM0815. This peripheral
shares one interrupt request for both directions (ie. transmit/receive) of data transfer, so
outgoing and incoming data should be synchronized for FIFO fill and empty.
1 In order to send control data to the external modem codec, program the control register
to drive nCON output pin to LOW and enable AFE.
2 Send control data by writing two words to the transmit FIFO. These four half words
have the same data to synchronize timing with codec.
3 When there is an interrupt request which indicates that FIFO needs to be filled, then
drive nCON pin HIGH, which represents that AFE is in normal data transfer mode.
Normally nCON pin should be HIGH.
4 Disable AFE to initialize FIFO.
5 To transmit and receive data, enable AFE (nCON pin should stay HIGH).
6 Write the outgoing data to the transmit FIFO. There will be no interrupt for the first
data request. The data size should be 1 + burst size of words (32 bit). If software
requires an eight-word burst, then it should write nine words first. Then write/read
eight words to/from transmit/receive FIFO on each interrupt. The burst size can be
selected from one to eight words.
7 For each FIFO fill interrupt request, write outgoing data and then read the incoming
data. FIFO over-/underrun error is checked only by transmit part, and incoming data
has more latency than outgoing data.
8 Interrupt should be serviced before one word (two data) transmit time.
9 The last word cannot be transmitted if AFE is disabled before completing a transfer.
To confirm it, include one filler word as the last one and wait until FIFO fill interrupt
request is generated.
If there is a FIFO error, software should disable AFE to initialize FIFO again.
GMS30C7201 Data Sheet
13-63