updates

2 files changed, 91 insertions, 40 deletions

diff --git a/design/hardware.page b/design/hardware.page
index 8101074..9da3c61 100644
--- a/design/hardware.page
+++ b/design/hardware.page
@@ -3,16 +3,42 @@
 
 ### Core
 
-*See [research/cpu]() for an overview of the **many** low-cost embedded
+*See [/research/cpu]() for an overview of the **many** low-cost embedded
 processors which have been announced, and a justification of this component
 selection.*
 
-The Freescale i.MX6 series ARM processors
+The Freescale i.MX6 series ARM processors are in production as of summer 2012,
+hardware-specific code is being upstreamed into the Linux kernel, and extensive
+public documentation will be released in November 2012. Several (but not all)
+variants are "pin-compatible", allowing upgrades. Rumored prices put the 1GHz
+"Dual Core Lite" processor at around $16/each for commerical-grade temperature
+ranges, or $21 for extended temperature ranges. The single core chip could go
+as low as $11/each in quantities of 10k.
 
-An external power management/regulator chip is required to provide stable
-voltage for this chip.
+These chips have plenty of power and storage connectivity to act as web
+servers. They should have enough connectivity throughput to fufil expectations
+of contemporary network routers. They have enough extra communications and
+system ports (SATA, SD, USB, video, audio, etc) to be expandable and hackable.
 
-### Wireless
+A dedicated power management/regulator chip ("PMIC") will almost certainly be
+required to provide stable voltage for the SoC. The vendor usually produces
+such a chip; for budgeting purposes i've included Freescale's equivalent PMIC
+for their i.MX53 line of processors.
+
+512MB should be adequate for almost all server applications. The i.MX6 chips
+support 64 bit bus widths for faster throughput, optionally through two 32 bit
+channels. RAM chips should be selected to take advantage of this.
+
+With enough RAM to cache the kernel and core daemons, micro SD flash storage
+should be sufficient for both a bootloader and core operating system. Disk
+storage can be expanded through a full-sized SD card slot, USB thumb drives, or
+a SATA port.
+
+On-board flash memory could be provided for a BIOS if that ends up being
+desired. FRAM memory could also be used to cache the kernel, DHCP tables, or
+other information to make reboots extremely fast. 
+
+### WiFi
 
 The miniPCIe slot allows flexibility in selecting an appropriate dual-band
 802.11n card; see [research/miniPCIe]() for a list of options and issues.
@@ -27,35 +53,61 @@ sells such a device new for $35, as does
 [netgate.com](http://store.netgate.com/WLE200NX-80211nabg-miniPCIe-Card-P1763C29.aspx)
 for $45. 
 
-An antenna would also be required; SparkFun sells adapters for
-[$5](https://www.sparkfun.com/products/662), so I will budget $5 for an adapter
-plus antenna.
-
-    - ARM SoC, Freescale i.MX6
-    - Power management/regulator IC for SoC
-    - 512MB RAM
-    - No onboard FLASH, 8GB+ uSD card
- - WiFi
-    - full-size miniPCIe slot for off-the-shelf dual-band card
- - 802.15.4 
-    - all-in-one stm32w chip, trace antenna (?)
- - Ethernet
-    - GigE switch chip w/ PHY, 5 ports
-    - 4x LAN jacks with drivers for longer cable runs (w/ LEDs)
-    - 1x WAN jack
- - Power
-    - 5/12v regulator, ~1amp
-    - Power connector
-    - Reverse voltage diode
- - USB Host jack
- - USB mini jack for UART/JTAG/Mass storage (how? USB2 hub?)
- - Second SD or uSD connector (for expansion)
- - status LEDs and drivers (PWM from SoC?)
- - reset button
- - power switch
-
-An alternative "minimal" feature set device is described at
-[design/minimal_design]().
+Antennas and cabling (for both 2.4GHz and 5GHz) are necessary and usually
+aren't included with PCI cards, so the rooter will need to ship with them.
+
+## Ethernet
+
+The Realtek RTL8366SR gigabit switch chip is an industry standard with support
+in OpenWRT. I have been unable to find a public price quote for it, but am
+confident that it can be sourced in smaller quantities (1k). For prototyping it
+could even be re-flowed off of a cheap commodity router.
+
+Extra analog circuitry to boost the current going out over long (50+ meter)
+ethernet cable runs may be required for reliability in extreme environments.
+
+The first revision rooter will probably not support power-over-ethernet;
+injector dongles provide similar functionality.
+
+## Connectivity
+
+For both initial development and for later hacking, JTAG access to at least the
+SoC will be broken out.
+
+A boot-time serial console is a very useful debugging and hacking interface,
+but RS-232 is a bit clunky to implement, and requires an extra adapter for
+users. As a contemporary solution, an FTDI chip will allow USB access to the
+root serial console, with low-voltage UART pins also broken out to pads
+internally.
+
+## Power
+
+12-20v DC input power will be accepted, with the explicit goal of being able to
+run off 12v battery or solar power without browning out down to 10.5v or so.
+
+rooter will probably pull between 2-5 watts when active, more depending on on
+USB, SATA, PCI, and other peripherals. Idle power usage should go very low. 
+
+TODO: a 12v power adapter is not included in the price estimate below, a decent
+one probably costs about $3 in bulk.
+
+## Extra Features
+
+rooter will include an 2.4GHz 802.15.4 radio on-board to enable lightweight
+"internet-of-things" communication with embedded devices. The 6lowpan protocol
+will be supported by default, libre implementations of the ZigBee protocol
+stack or other protocols could be installed by the user.
+
+A simple avalanche break-down circuit will provide a high-quality stream of
+random numbers to the main processor, to be mixed with other sources of entropy
+for cryptographic purposes.
+
+A user-programable microcontroller with both an On-The-Go USB port and
+connectivity to the main processor will enable real-time programming and other
+such hackery. For example, IP-over-USB for devices without an ethernet port,
+interfacing to non-IP communication buses, USB mass-storage pass through,
+low-bandwidth wireless radio protocol experimentation (433MHz, 900MHz, etc),
+out-of-band network data monitoring, secret sharing, etc.
 
 ## Proposed BOM and Costs (August 2012)
 
diff --git a/design/overview.page b/design/overview.page
index 9337a12..354b6d1 100644
--- a/design/overview.page
+++ b/design/overview.page
@@ -45,15 +45,14 @@ protocol (eg 802.15.4 6lowpan, ZigBee, Bluetooth Low-Energy, etc).
 
 See [design/hardware]() for specific components and costs.
 
-- 1GHz ARM SoC processor (possibly dual-core)
+- 1GHz dual-core ARM SoC processor
 - 512MB RAM
 - Internal uSD card storage, expandable through SATA and USB ports
-- Modular WiFI via miniPCIe slot
-- Second USB-only miniPCIe slot for expansion
-- 2+ powered USB ports for expansion
+- Modular WiFI via miniPCIe slot; recommend dual-band 802.11n
+- 2 powered USB ports for expansion
 - 5x Gigabit ethernet ports: 4x local + 1x upstream
-- Serial and JTAG debugging via USB port
-- Low-power "internet of things" gateway with 802.15.4 radio 
+- Serial and JTAG debugging via micro-USB port
+- Low-bandwidth "internet of things" gateway with 802.15.4 radio 
 - Hardware entropy generation device
 
 ## Comparison