Grandstream GXP-2020
DSP processor, 2 MB Flash, 4 MB RAM, network, switch
This hardware chart is partially done.
This page describes the printed circuit board of the phone.
Related information can be found on the generic GXP page and
on the GPIO page.
The GXP2020 PCB is used in the following device models:
This manufacturer also produces other models.
- DSP system-on-chip: Covered in paint. This is a TMS320VC5501PGF.
- A coprocessor 320AIC20K from Texas Instruments interfaces speaker,
microphone and line in/out to the DSP over I2C or S2C. It includes
support for oversampling and filtering.
- Flash memory: 1024k x 16, or 2048k x 8: EN29LV160AB-70TCP.
Its 70 nS cycle time makes this flash memory suitable to run programs
from, so a smaller RAM size is possible.
- SDRAM: 2048k x 16, or 4096k x 8: 2x W9816G6CH-6. Supports speeds
up to 166 Mhz.
- Ethernet: RTL8019AS and on the models with a second ethernet
connector also (TODO). The RTL8019AS is an NE2000 clone, albeit
a bad one according to the Linux kernel. It does not really
matter; at least example code is available in that kernel, and
actually uIP has already been ported to these chips before.
- Switch: RTL8305SC with support for 5 ports, with up to 2 MII ports.
It would seem that the DSP processor needn't concern itself with
passing traffic between the LAN and WAN interfaces. It is even
possible that the DSP processor is fully unaware of any network
hardware other than the main ethernet device.
These are described centrally in more detail:
- J401 is a JTAG connector TODO:VERIFY which looks the same as on BT200 boards
- EXT is an I2C connector, including 3V3 supply and pins to influence booting over I2C.
I've been looking everywhere for I2C but never expected to find it externally
accessible ;-) but in fact it makes a lot of sense -- for an extension connector.
The JTAG connector used in these Grandstream phones is a 14-pin connector.
Its solder islands are open on the PCB, so soldering in a 0.1" pitched
two-row pin header is easy.